Junior Application Packet

Ru(II) Thioether Complexes in Self-Assembled Molecular Structures
By
Marko Bajic
Departmental Honors Thesis
The University of Tennessee at Chattanooga
Department of Chemistry
Project Director: Dr. Grant
Examination Date: April 5, 2010
Committee Members:
Dr. Gary McDonald
Dr. Robert Mebane
Dr. Thomas Rybolt
Examining Committee Signatures:
______________________________________________________________________
Project Director
______________________________________________________________________
Department Examiner
______________________________________________________________________
Department Examiner
______________________________________________________________________
Liaison, Departmental Honors Committee
______________________________________________________________________
Chairperson, University Departmental Honors Committee
Dedication
To my father Ranko Bajic and my mother Slava Bajic, who risked everything coming
to the United States of America so that we may have a better chance at life than was
possible in the war-torn region of Croatia, Bosnia, and Serbia. May this work reflect
their ability to endure, hope, and love.
1
Abstract
The major objective of this research is the preparation of metal thiacrown
complexes that will self-assemble with connecting ligands into molecular structures,
such as squares, cubes, triangles, or hexagons. These self-assembled structures are
controlled by the thiacrowns coordinated to the ruthenium(II) center. The thiacrowns
9S3 (1,3,7-trithiacyclononane), 12S4 (1,4,7,10-tetrathiacyclodentate), and 16S4
(1,5,9,13-tetrathiacyclohexadecane) were used to control the bond angles and geometry
of the ruthenium(II) complexes. The self-assembled complexes have important
applications in chemistry due to their wide use throughout electrochemistry, hydrogen
storage, and host-guest chemistry.
The procedure used throughout this research depends upon the removal of the
chlorides from the ruthenium thiacrown complexes in order for self-assembly to occur.
Herein we report the results of using Ag and Tl salts to dechlorinate. It was found that
AgCF3SO3 was able to dechlorinate all three ruthenium thiacrown complexes.
The [Ru(16S4)]2+ complex, which was dechlorinated using AgCF3SO3, was
then reacted with two different connecting ligands, one of which yielded a triangle. The
NMR spectroscopy of the triangle complex [{Ru(16S4)}3(μ-4,7-phen)3](CF3SO3)6 is
reported.
The inability to dechlorinate [Ru(12S4)]2+ fully with TlPF6 resulted in the
synthesis of a binuclear complex, [{Ru(12S4)Cl}2(μ-pyr)](PF6)2. The binuclear
complex was characterized with NMR spectroscopy, elemental analysis and X-ray
2
diffraction. We also report the synthesis of a dark red binuclear complex
[{Ru(9S3)(CH3CN)}2(μ-tpp)](PF6)2.
The other area of this research dealt with the synthesis of platinum diimine
thiacrown complexes. There were five diimine ligands utilized in the synthesis of these
complexes. These ligands are: 5,6-dimethyl-1,10-phenanthroline, 4,7-dimethyl-1,10phenanthroline, 4,7-diphenyl-1,10-phenanthroline, 5-nitro-1,10-phenanthroline, and
2,2’-biquinoline. Through this research, the complex [Pt(9S3)(5,6-dm-phen)](PF6)2
was fully characterized.
3
Table of Contents
Dedication…………………………………………………………………………
1
Abstract……………………………………………………………………………
2
Table of Contents…………………………………………………………………
4
Acknowledgements………………………………………………………………..
5
Introduction……………………………………………………………………….
7
Experimental
Materials…………………………………………………………………..
32
Measurements…………………………………………………..…………
33
Ru(II) Chemistry………………………………………………………….
34
Pt(II) Chemistry…………………………………………………………..
63
Pd(II) Chemistry………………………………………………………….
67
Cancer Screening…………………………………………………………
68
Results and Discussion
Thiacrown Addition………………………………………………………
70
Ruthenium Thiacrown Dechlorination………………………………….
79
Binuclear Complexes……………………………………………………..
85
Self-Assembly……………………………………………………………...
93
Platinum Thiacrown Complexes with Substituted Diimine Ligands….
98
Cancer Screening………………………………………………………… 112
Conclusions……………………………………………………………………….. 114
4
Acknowledgements
I would like to thank Dr. Gregory J. Grant, who believed in me as a young
freshmen, mentored me as I developed my chemistry knowledge, and encouraged me
as we fought against the competition to develop novel compounds. I will always be
thankful for your faith, mentorship, and support over these last four years.
I would also like to thank Dr. Greg Grant, Dr. Gary McDonald, Dr. Robert
Mebane, and Dr. Thomas Rybolt for kindly serving on my Departmental Honors
Committee and for their constructive criticism, which has been essential in developing
this thesis.
I would like to thank Dr. Gail Meyer, Dr. Thomas Rybolt, and the Department
of Chemistry at the University of Tennessee at Chattanooga for their mentorship and
support as I progressed as a Chemistry major.
I would like to thank Dr. Donald VanDerveer at Clemson University for his
work in performing and analyzing our X-ray crystallography, and Dr. Will Setzer at
University of Alabama-Huntsville for performing our cancer screening analysis.
Furthermore, I would like to thank the current and past members of the Grant Group
for their support and for laying the foundation for this project.
5
In terms of monetary supports, I would like to thank the American Chemical
Society Petroleum Research Fund, the Grote Chemistry Fund, the National Science
Foundation (RUI Program), the UTC Provost Student Research Award, and Research
Corporation.
6
Introduction
A. General
The modern world economy is driven by energy sources that are constantly
being depleted. Renewable forms of energy, such as ethanol, are being developed to
compensate for the diminishing amounts of oil and fossil fuels that are available.
Hydrogen, due to its light weight, high abundance and safe reaction byproduct is the
ideal way to store energy.1 Hydrogen produces water as the byproduct when used as a
fuel, compared to carbon dioxide and carbon monoxide produced by the use of carbonbased fuels. However, hydrogen’s nature as a gas makes it difficult to store efficiently.
The gas is expensive to store due to the low storage amount to price ratio and the
constant loss of the gas.1
In the past, there have been two main ways of storing hydrogen: in compressed
hydrogen gas tanks or in liquid hydrogen tanks.2 These tanks are small enough to be
installed into automobiles, providing hydrogen as the fuel that powers a fuel cell,
which supplies electricity to the motor and propels the automobile.3 This process is
shown in Figure 1:
______________________
Schlapbach, Louis; Züttel, Andreas. “Hydrogen-storage Materials for Mobile
Applications.” Nature. 2001, 414, 23-31.
2
Cutler, Cleveland J. “Hydrogen storage” The encyclopedia of earth. October 20,
2009. <http://www.eoearth.org/article/hydrogen storage>.
3
“Hydrogen Fuel” AE Hydrogen Fuel. October 20, 2009. <http://www.alternativeenergy-news.info/technology/hydrogen-fuel/>.
1
7
Figure 1: Hydrogen Fuel Cell
http://www.alternative-energy-news.info/technology/hydrogen-fuel/
Figure 1: A hydrogen-containing vessel provides molecular hydrogen that is
used as fuel for the fuel cell. A catalyst within the fuel cell splits the molecular
hydrogen into protons and electrons. The protons travel across the electrolyte
towards the cathode. Electrons are directed through an external circuit,
generating an electrical current that can do work. Multiple fuel cells are
arranged together to make a fuel cell stack used in automobiles.
However, the use of compressed hydrogen gas tanks and liquid hydrogen tanks
is limited by several factors. A compressed hydrogen gas tank is a 3-layer tank design
that compresses molecular hydrogen in its gaseous state.2 Issues faced with this design
are 1) high amounts of pressure are needed to fill the tanks with hydrogen, 2) the tank
has a large weight, 3) a small amount of hydrogen is stored compared to the large size
of the tank, and 4) the tank is not very stable to withstand a lot of pressurized
hydrogen.2 These issues can be resolved by lowering the temperature in order to slow
8
down the rapidly moving hydrogen gas molecules, but this requires the use of
expensive cryogenics.2
The use of liquid hydrogen tanks to store hydrogen faces similar challenges and
expensive solutions. Liquid hydrogen tanks store hydrogen in its liquid state. They are
able to store more hydrogen than compressed gas tanks.2 The problems facing liquid
hydrogen tanks are that liquid hydrogen readily boils off, and it is expensive to keep
this from happening.2
An ideal way to use hydrogen would be as a gas so it can be readily stored,
without using large amounts of pressure, and released. This goal can be achieved by
using well-designed tanks that reduce the concern of large amounts of hydrogen
rupturing the tank. Fortunately, recent literature has shown that metal organic
frameworks, or MOFs, can be used to store hydrogen as a liquid or solid.4 MOFs have
a porous nature and unusually high surface areas that show great H2 uptake compared
to their mass.4 Hydrogen stored this way requires less storage volume and is less
expensive because huge amounts of pressure are not required to minimize volume.
Research similar to the synthesis of MOFs has also shown that covalent organic
frameworks, of COFs, can be used to readily store hydrogen, methane, and even carbon
dioxide.5 The difference between MOFs and COFs is that in COFs there are no metal
centers directing the geometry of the final product. Instead, nonmetals like boron,
___________________________
Brown, Craig M.; Dailly, Anne; Dinca, Mircea; Long, Jeffrey R.; Neumann, Dan. A.
“Hydrogen Storage in a Microporous Metal-Organic Framework with Exposed Mn2+
Coordination Sties.” J. Am. Chem. Soc. 2006, 128, 16876-16883.
4
9
silicon, and carbon are used to make frameworks with various ligands.5 These
frameworks are repeating units of a distinct unit. When boron is used, the framework
makes a 2-D repeating structure with either small or large pores where a gas molecule
can be stored.5 When carbon or silicon is used to connect the units the resulting
framework has a cavernous 3-D shape with medium holes.5
What is amazing is the difference in storage in a given volume when MOFs or
COFs are present compared to when they are absent6. Figure 2 shows this relationship:
Figure 2: CO2 Storage Comparison for MOF-177
http://www.greencarcongress.com/2005/12/metalorganic_fr.html
Figure 2: A tank filled with MOF-177 can store as much CO2 as nine tanks devoid
of MOF-177.
___________________________
5
Furukawa, H.; Yaghi, O. “Storage of Hydrogen, Methane, and Carbon Dioxide in
Highly Porous Covalent Organic Frameworks for Clean Energy Applications.” J. Am.
Chem. Soc. 2009, 131, 8875-8883.
6
“Metal-Organic Frameworks for Hydrogen Storage…and CO2 Capture” Green Car
Congress. October 20, 2009.
<http://www.greencarcongress.com/2005/12/metalorganic_fr.html>.
10
B. Ruthenium Complexes
My research takes advantage of these types of molecules by focusing on the
self-assembly of ruthenium(II) molecular structures which are crystalline solids that
have porous, chemically controlled geometries. Self-assembly is the spontaneous
combination of various components, under controlled conditions, into an organized
shape. Unlike a regular reaction, self-assembly is favored due to the formation of
stronger chemical bonds, but is disfavored due to a decrease in entropy, randomness, as
the many constituents combine into a single product. Self-assembly differs from a
regular reaction in the sheer complexity of the reactants and final product. The
macromolecules formed are very complex, yet ordered structures.
Ruthenium(II) molecular structures are formed through the self-assembly of
ruthenium(II) metal corners and two types of ligands. Ligands are molecules that
covalently share electrons with a central metal atom. One type of ligand forms bonds
with the metal in order to control the metal and stabilize it’s geometry at a 90° angle.
The other type of ligand bridges the corners and forms the sides of the square. Our
group has successfully built, monitored, and characterized molecular squares
previously.7
The goal of this research is to synthesize molecular squares that could be used
to store hydrogen by encapsulating the hydrogen in the porous cavity of the complex.
______________________
Janzen, Daron E.; Patel, Ketankumar N.; VanDerveer, Donald G.; Grant, Gregory J.
“Synthesis and structure of a platinum(II) molecular square incorporating four
fluxional thiacrown ligands: The crystal structure of [Pt4([9]aneS3)4(4,4-bipy)4](OTf)8.”
Chem. Commun. 2006, 33, 3540-3542.
7
11
However, other molecular geometries have also been reported that could be used to
store hydrogen. These include similar molecular squares,8,9 a molecular cube,10 a
molecular cage,11 and molecular triangles.9,12 Though their geometric structures may be
different the basic approach to their synthesis is the same; incorporation of the two
different ligand types and the reactive transition metal, ruthenium(II). This synthesis is
similar to the one used in this research. Because the syntheses are similar, the final
products may turn out to be something besides a square. These other geometric shapes
could also have possible hydrogen storage capabilities.
Hydrogen storage is not the only application for the self-assembled complexes.
A self-assembled ruthenium cage reported by Fujita has shown properties that could be
used to make a sensor whereby the complex changes color when it encapsulates a
certain molecule10. This process is illustrated in Figure 3:
______________________
Long, Jeffrey R.; Berben, Louise A.; Lau, Victor C. “[(Cyclen)4Ru4(pz)4]9+: A
Creutz-Taube Square.” JACS Comm. 2002, 124, 9042-9043.
9
Long, Jeffrey R.; Crawford, Nathan, R. M.; Faia, Mary C.; Berben, Louise A.
“Angle-Dependent Electronic Effects in 4,4’-Bipyridine-Bridged Ru3 Triangle and
Ru4 Square Complexes.” Inorg. Chem. 2006, 45, 6378-6386
10
Thomas, Jim A.; Heath, Sarah L.; Adams, Harry; Haslam, Claire; Roche, Sue. “Selfassembly of a supramolecular cube.” Chem. Commun. 1998, 1681-1682.
11
Fujita, Makoto; Kawano, Masaki; Yamashita, Ken-ichi. “Ru(II)-cornered
coordination cage that senses guest inclusion by color change.” Chem. Commun. 2007,
4102-4103.
12
Alessio, Enzo; Casanova, Massimo; Jedner, Stephanie; Bratsos, Ioannis; Ravlico,
Francesco; Kulisic, Niksa; Zangrando, Ennio. “New ruthenium(II) precursors with the
tetradentate sulfur macrocycles tetrathiacyclododecane ([12]aneS4) and
tetrathiacyclohexadecane ([16]aneS4) for the construction of metal-mediated
supramolecular assemblies.” Inorganica Chimica Acta. 2009, 362, 820-832.
8
12
Figure 3: Sensor Properties of Self-assembled Cage
M. Fujita Chem. Commun. (2007) 4102
Figure 3: The cage changes color in a water solution, from yellow, to red as it
encapsulates 1-adamantanol molecules.
The ability of ruthenium to have 2+ or 3+ oxidation states allows it to have
interesting electrochemical properties. These properties have been examined in the
synthesis of a Creutz-Taube ion7 and binuclear complexes.13,14 This electrochemical
property of ruthenium could be used to control the electron density of the self
assembled complex by either oxidizing or reducing the corners. If the coordination
sites on the ruthenium are trans to each other, it can also be used to synthesize
nanowires. For this type of communication from one ruthenium thiacrown molecule to
the other to occur the ruthenium thiacrown molecules have to be bridged by flat,
electron rich ligands. This requirement for a specific linker ligand was described in
______________________
13
Grant, Gregory J.; Mehne, Larry F.; VanDerveer, Donald G.; Chen, Weinan; Janzen,
Daron E. “Synthesis and structural studies of ruthenium(II) 12S4 complexes with 4,4’bipyridine: The crystal structures of [Ru(12S4)(bpy)Cl](Cl) · H2O and
[{Ru(12S4)Cl}2-μ-(bpy)](PF6)2 · 2CH3CN.” Inorg. Chem. Comm. 2006, 992-995.
14
Thomas, Jim A.; Ward, Michael D.; Adams, Harry; Vickers, Steven J.; Easun,
Timothy L.; Ingram, James D.; Newell, Mike. “Structure and Properties of Dinuclear
[RuII([n]aneS4)] Complexes of 3,6-Bis(2-pyridyl)-1,2,4,5-tetrazine.” Inorg. Chem.
2006, 45, 821-827.
13
Long’s paper where he showed that a strained (flat) 4,4’-bipyridine in a self assembled
triangle allowed for communication between the Ru(12N4) corners, while a twisted
(not flat) 4,4’-bipyridine in a self assembled square showed no communication.8 This
relationship is shown in Figure 4:
Figure 4: Ligand Requirements for Communication
J. R. Long Inorg. Chem. (2006) 6385
Figure 4: The square on the left is bridged by 4,4’-bipyridine which has a torsion
angle between the two pyridine groups of 37.2°. This means that even though 4,4’bipyridine is electron rich there is no communication between the ruthenium
corners because the ligand is not flat. In the triangle on the right the structure is
strained and 4,4’-bipyridine has to twist in order to accommodate for this strain. In
doing so it loses the torsion angle and becomes flat. Because of this there is
communication between the ruthenium corners of the triangle.
14
The process of self-assembly occurs in three stages:
1. Formation of the metal corner by adding the appropriate thioether.
2. Removal of all chloride from the metal corner to provide an open site for a
linker.
3. Reaction of the chloride-free metal corner with the appropriate side linker to
form the molecular square, triangle, cube, or hexagon.
This process is illustrated in Figure 5:
Figure 5: Self-assembly Pathway
Figure 5: The three stages of self-assembly are illustrated above. The spheres in the product
represent the metal thiacrown complex: Ru(9S3) in the cube, Ru(12S4) in the square, and
Ru(16S4) in the hexagon or triangle.
15
The first part of the synthesis towards self-assembly involves complexing
thiacrown ethers onto the starting ruthenium complex, [Ru(dmso)4Cl2], that is available
commercially. The three thiacrowns used for this research were 12S4 (1,4,7,10tetrathiacyclododecane), 9S3 (1,4,7-trithiacyclononane), and 16S4 (1,5,9,13tetrathiacyclohexadecane). These ligands are favorable for the formation of a
ruthenium corner molecule because they bind very strongly to the metal due to the
strong binding of ruthenium to sulfur. This makes it much easier to run reactions after
they are bound because there is little worry of the thiacrowns being replaced by a
different ligand. The three thiacrowns used in this research are shown in Figure 6:
Figure 6: Thiacrown Ligands
(12S4)
1,4,7,10-tetrathiacyclododecane
………………………………………………………………………………………………
(9S3)
1,4,7-trithiacyclononane
………………………………………………………………………………………………
16
(16S4)
1,5,9,13-tetrathiacyclohexadecane
Figure 6: Thiacrown ligands used in this research
The thiacrowns also hold the ruthenium complexes in fixed angles; 90°
between the two free sites of the ruthenium when 12S4 is bound, 90° between the three
free, face-capping, sites of the ruthenium when 9S3 is bound, and 180° between the
two free sites of the ruthenium when 16S4 is bound. We refer to a site as free when a
labile ligand is bound to it. These geometries are shown in Figure 7:
Figure 7: Geometry of Ruthenium Thiacrown Starting Complexes
Ru(12S4)
Ru(9S3)
Ru(16S4)
Figure 7: The Ru(12S4) corner has two sites for ligand bonding that are 90° to each other.
The Ru(9S3) corner has three sites for ligand bonding, two are 180° and each is 90° to the
third open site. The Ru(16S4) corner has two sites for ligand bonding that are 180° to
each other.
17
Also, these thiacrowns have characteristic NMR spectra. Though their
methylene proton peaks can be complicated and vary with what type of Ru compound
they are found in, their carbon peaks are more indicative. The ligand 9S3 will have one
peak for 13C NMR, 16S4 will have two peaks, and 12S4 will have four peaks. 12S4 has
four 13C NMR peaks because of the invertomers present on the thiacrown’s sulfurs.8
Invertomers are defined as metal complexes that are stereoisomers, but have differing
orientations of lone pair electrons on the ligating atoms. Figure 8 illustrates the
invertomer observed so far that produces the four carbon peaks.
Figure 8: Ru(12S4) Invertomer
Figure 8: Observed invertomer of Ru(12S4) complexes.
After the thiacrowns have been added to the Ru, the chlorides that are strongly
bonded to the ruthenium need to be removed prior to addition of connector ligands.
The chlorides will be subsequently replaced with labile ligands. Three different salts
were used to dechlorinate the starting ruthenium thiacrown complexes. It was found
that AgCF3SO3 (silver triflate) was able to dechlorinate all three of the starting
ruthenium thiacrown complexes. The removed chlorides reacted with silver to form the
18
highly insoluble AgCl.8 The vacant site was replaced with a solvent molecule, and the
CF3SO3- anion acted as a counter anion compensating for the increased charge of the
overall complex.
The next step of the self-assembly synthesis is the attachment of the desired
linker ligand. The exact conditions for this step have still not been completely
perfected. The factors that must be taken into account are the solvents to be used, the
amount of time to reflux, the reflux temperature, and whether the reaction should be
run under nitrogen. We have looked at water/methanol (1:1) as the solvent and 5 hour
reflux as the time to perform the experiment. Some experiments were run for 24 hours
because the obtained products did not go to completion, but instead partially selfassembled complexes were obtained.
Labile ligands are those that coordinate weakly to the ruthenium metal. This means
that they will be easily displaced by a ligand that forms a stronger bond with the
ruthenium metal, such as a linker ligand. The ligands that form stronger bonds are the
thiacrown ligands and the linker ligands. The labile ligands used in this research are
reported in Figure 9:
Figure 9: Labile Ligands
water
nitrate ion
dimethyl sulfoxide
Figure 9: Labile ligands used throughout this research. Labile ligands form weak
bonds with ruthenium (II) and are readily displaced by ligands that bind stronger.
19
The strongly bonding connecting ligands are shown in Figure 10:
Figure 10: Connecting Ligands
(bipy)
4,4’-bipyridine
………………………………………………………………………………………………
(pyr)
1,4-pyrazine
………………………………………………………………………………………………
(fum)
fumaronitrile
………………………………………………………………………………………………
(dcn)
1,4-dicyanobenzene
………………………………………………………………………………………………
(bpe)
1,2-bis(4-pyridyl) ethane
20
………………………………………………………………………………………………
(pmd)
pyrimidine
………………………………………………………………………………………………
(4,7-phen)
4,7-phenanthroline
………………………………………………………………………………………………
(tpp)
tetra-(2-pyridyl)pyrazine
Figure 10: Connecting ligands used in this research
From the above connecting ligands, the common theme is that the bonding to
the ruthenium comes from the nitrogen atoms. In all of the above ligands, besides
21
pyrimidine and 4,7-phenanthroline, the nitrogens are located 180° from each other.
This orientation is ideal for these ligands to be used as sides in a self assembled square
or cube. The ligand pyrimidine has the nitrogens located at a 120° angle from each
other. This orientation prevents the ligand from being used in a square or cube selfassembly. However, the 120° angle is ideal for a hexagon self-assembly. The ligand
4,7-phenanthroline has the nitrogens located at a 60° angle from each other. This
makes it idea for a triangle self-assembly. There is some deliberation whether a 4,7phenanthroline and Ru(16S4) self-assembled complex is considered a triangle or
hexagon. If the sides of the 4,7-phenanthroline ligand are counted as the sides of the
overall complex then the product is considered a hexagon. However, if only the linear
Ru(16S4) is considered when counting the sides then the product composed of three
4,7-phenanthroline and three Ru(16S4) is considered a triangle.
As mentioned earlier, in order for there to be communication between
ruthenium thiacrown corners, the ligand that is bridging them must be planar and
electron-rich. These two requirements are met if the ligand has conjugated double
bonds. Of the connecting ligands listed above, the only ligand that does not have this
criteria is the 1,2-bis(4-pyridyl) ethane. This ligand was used to determine whether it
would be possible to bridge ruthenium corners with a ligand that had some freedom of
movement. As for the other ligands there are two that have conjugated double bonds
between the nitrogens but are not flat, planar ligands. These two ligands are 4,4’bipyridine and tetra-(2-pyridyl)pyrazine.
22
The 4,4’-bipyridine was widely used in this research because it has a
characteristic proton NMR spectra and has been cited many times as a good bridging
ligand.7, 9, 10, 13, 15, 16 As mentioned earlier, the 37.2° torsion angle of 4,4’-bipyridine can
be controlled depending on what the self-assembled structure is.
The tetra-(2-pyridyl)pyrazine was used to test whether it was possible to
incorporate all six nitrogens of the ligand in bridging two Ru(9S3) corners. The large
amount of conjugation would make for an interesting electrochemical study.
C. Pt and Pd Chemistry
Platinum (II) and palladium (II) complexes are widely used for catalysis and
electrochemical studies.17, 18, 19, 20 The focus of this portion of the research is the
synthesis and characterization of novel platinum or palladium thioether complexes. The
______________________
15
Alessio, Enzo; Calligaris, Mario; Geremia, Silvano; Mestroni, Giovanni; Iengo,
Elisaetta. “Novel ruthenium(III) dimers Na2[{trans-RuCl4(Me2SO-S)}2(μ-L)] and
[{mer, cis-RuCl3(Me2SO-S)(Me2SO-O)}2(μ-L)] (L = bridging heterocyclic N-donor
ligand) closely related to the antimetastatic complex Na[trans-RuCl4(Me2SOS)(Him)].” J. Chem. Soc. Dalton Trans. 1999, 3361-3371.
16
Thomas, Jim A.; Felix, Victor; Ward, Michael D.; Vickers, Steven J.; Newell, Mike;
Costa, Paulo J.; Adams, Harry. “Mixed Valence Creutz-Taube Ion Analogues
Incorporating Thiacrowns: Synthesis, Structure, Physical Properties, and
Computational Studies.” Inorg. Chem. 2008, 47, 11633-11643.
17
Rosenblatt, Edgar F. “Hydrogenation of Quinone with Palladium and Platinum
Catalysts.” J. Am. Chem. Soc. 1940, 62 (5), 1092-1094.
18
Ullman, Edwin F. “Mechanism of Hydrogenation of Unsaturated Cyclopropanes.” J.
Am. Chem. Soc. 1959, 81 (20), 5386-5392.
19
Eisenberg, Richard; Knowles, Kathryn; Du, Pingwu. “A Homogeneous System for
the Photogeneration of Hydrogen from Water Based on a Platinum(II) Terpyridyl
Acetylide Chromophore and a Molecular Cobalt Catalyst.” J. Am. Chem. Soc. 2008,
130, 12576-12577.
20
Moore, Thomas A.; Moore, Ana L.; Ghirardi, Maria; Gust, Devens; King, Paul W.;
Svedruzic, Drazenka; Gervaldo, Miguel; Hambourger, Michael. “[Fe-Fe]Hydrogenase-Catalyzed H2 Production in a Photoelectrochemical Biofuel Cell.” J. Am.
Chem. Soc. 2008, 130, 2015-2022.
23
research that will be discussed here will be that of platinum (II) thioether complexes
with substituted diimine ligands. The general synthesis of these complexes is outlined
in Figure 11:
Figure 11: Platinum Thioether Diimine Synthesis
Figure 11: Synthesis of platinum thioether complexes with substituted diimine ligands. The
first step is the addition of 9S3. The second and last step is the addition of the specific diimine
ligand to the platinum thiacrown compound.
The first step involves the addition of 9S3 to the starting complex cis[PtCl2(NCPh)2]. What is interesting to note is that the 9S3 has three available sites for
binding to the platinum. However, the d8 metal ion, platinum(II), prefers the square
24
planar geometry and has only two sites that the 9S3 can displace. Labile NCPh2 ligands
are easily displaced by the 9S3, but the thiacrown ligand is not able to readily displace
the chlorides. The interesting point to be made is that there are three 9S3 sulfurs
competing for binding to the two open sites on the platinum metal. This causes what
Martin Schroder termed an “orbital mismatch.”21 This phenomena is shown in Figure
12:
Figure 12: Orbital Mismatch Between Pt and 9S3
Figure 12: The orbital mismatch gives rise to fluxionality where the thiacrown, 9S3, spins
as the sulfurs exchange their positions. The numbers are arbitrarily numbered because the
spinning is circular and can be in either direction. Seq stands for equatorial sulfurs and Sax
stands for axial sulfurs.
The result of the orbital mismatch is that the 9S3 sulfurs undergo an
intermolecular exchange known as fluxionality. During this fluxionality, the equatorial
sulfurs rapidly replace the axial sulfur and the cycle repeats. Because of this there will
be a single 13C NMR signal for [Pt(9S3)]2+.
________________________
Blake, A. J., Holder, A. J., Hyde, T. I., Robers, Y. V., Lavery, A. J., Schroder, M. J.
“Structural and Electrochemical Studies of Trithia Macrocyclic Complexes of
Palladium.” Organomet. Chem., 1987, 323, 261.
21
25
The final step of the synthesis of these platinum thioether complexes is the
addition of a diimine ligand to the platinum thiacrown complex. The diimine ligands
used in this research are shown in Figure 13:
Figure 13: Diimine Ligands
(5,6-dm-phen)
5,6-dimethyl 1,10-phenanthroline
………………………………………………………………………………………………
(4,7-dm-phen)
4,7-dimethyl 1,10-phenanthroline
………………………………………………………………………………………………
26
(4,7-dph-phen)
4,7-diphenyl 1,10-phenanthroline
………………………………………………………………………………………………
(5-nitro-phen)
5-nitro 1,10-phenanthroline
………………………………………………………………………………………………
(bqn)
2,2’-biquinoline
Figure 13: Diimine ligands used in this research to synthesize the platinum thioether
complexes with substituted diimine ligands.
It can be seen from the ligands above that all of them are phenanthrolines
except for 2,2’-biquinoline. However, the 2,2’-biquinoline ligand shares the same 5-
27
membered chelate ring structure as all the other ligands. Therefore, the general ligand
binding to platinum is similar for all the diimine ligands. The ligands shown are
particularly interesting because they vary mostly in the location and identity of the
functional group present on the 1,10-phenanthroline. It is interesting how these
differences affect the characteristics of the final product.
D. Cancer Screening
The main focus of the research project deals with either making self-assembled
complexes for use in fuel storage or creating thioether complexes to be analyzed for
interesting properties. Another area that my research has focused on was the
development of new compounds to fight cancer. Cisplatin has been shown to be
effective in treating testicular cancer, with a cure rate of 90% when tumors are
diagnosed early.22 Cisplatin closely resembles the structure of cis-[Pd(9S3)Cl2] that I
prepared while performing this research. Another complex made by Enzo Alessio’s
group showed capability to stop the growth of mouse adenocarcinoma cancer cells.23
The complex made by Alessio’s group was [Ru(9S3)(en)Cl]OTf, where en means
ethylenediamine. This complex is very similar to a complex I prepared throughout this
research; that of fac-[Ru(9S3)(dmso)Cl2]. The compounds that are similar in geometry
_______________________
Bosl, G. J.; Motzer, R. J. “Testicular Germ-Cell Cancer” N. Engl. J. Med. 1997, 337,
242-253.
23
E. Alessio, B. Serli, E. Zangrando, T. Gianferrara, C. Scolaro, P. J. Dyson, A.
Bergamo. “Is the Aromatic Fragment of Piano-Stool Ruthenium Compounds an
Essential Feature for Anticancer Activity? The Development of New RuII-[9]aneS3
Analoguees” Eur. J. Inorg. Chem. 2005, 3424-3434.
22
28
were tested to determine their effectiveness at killing cancer cells. The structures tested
and those mentioned from literature are shown in Figure 14:
Figure 14: Cancer Screening Compounds
Cisplatin
cis-[Pd(9S3)Cl2]
[Ru(9S3)(en)Cl]+
fac-[Ru(9S3)(dmso)Cl2].
Eur. J. Inorg. Chem. 2005, 3424-3434
Figure 14: The compounds reported to be effective at fighting cancer are reported on
the left. The analog compounds made as part of the thesis are reported on the right.
29
The following outline shows the topics that will be covered in this thesis.
I. Ruthenium (II) Chemistry
A. 12S4 (1,4,7,10-tetrathiacyclododecane)
1. Corner Formation
a. cis-[Ru(12S4)(dmso)Cl]Cl
b. cis-[Ru(12S4)(dmso)Cl]PF6
2. Dechlorination of corner complex
a. Thallium hexafluorophosphate
b. Silver nitrate
c. Silver triflate
3. Self-assembly of tetranuclear complexes
a. 4,4’-Bipyridine
b. 1,4-Pyrazine
c. 1,2-Bis(4-pyridyl) ethane
d. 1,4-Dicyanobenzene
e. Fumaronitrile
4. Synthesis of binuclear complexes
a. 1,4-Pyrazine
b. 1,2-Bis(4-pyridyl) ethane
B. 9S3 (1,4,7-trithiacyclononane)
1. Corner Formation
a. fac-[Ru(9S3)(dmso)Cl2]
2. Dechlorination of corner complex
a. Thallium hexafluorophosphate
b. Silver triflate
c. Silver hexafluorophosphate
3. Binuclear Complexes
a. tetra-(2-pyridyl) pyrazine
4. Self-Assembly
a. 4,4’-Bipyridine
b. 1,4-Pyrazine
C. 16S4 (1,5,9,13-tetrathiacyclohexadecane)
30
1. Side Formation and Dechlorination
a. trans-[Ru(16S4)(dmso)(H2O)](CF3SO3)2(dmso)
2. Self-Assembly
a. 4,7-Phenanthroline
b. Pyrimidine
II. Platinum (II) Chemistry
A. Corner Synthesis
1. cis-[Pt(9S3)Cl2]
B. Platinum Thiacrown Complexes with Substituted Diimine Ligands
1. 5,6-dimethyl, 1,10-phenanthroline
2. 4,7-dimethyl, 1,10-phenanthroline
3. 4,7-diphenyl, 1,10-phenanthroline
4. 5-nitro, 1,10-phenanthroline
5. 2,2’-biquinoline
III. Palladium (II) Chemistry
A. Corner Synthesis
1. cis-[Pd(9S3)Cl2]
B. Self-assembly
1. 4,4’-bipyridine
IV. Cancer Screening
A. cis-[Pd(9S3)Cl2]
B. fac-[Ru(9S3)(dmso)Cl2]
Hence, this research contains work on the progress towards self-assembled
ruthenium (II) thioether molecular structures. Next, a discussion on work with platinum
(II) self-assembly and platinum (II) thiacrown complexes with substituted diimine
ligands, followed by work on palladium (II) self-assembly. The final discussion deals
with work done testing the cancer killing abilities of various dichloro species.
31
Experimental
Materials:
The compounds: [Ru(dmso)4Cl2] (tetrakis(dimethylsulphoxide)dichloro
ruthenium(II)), 12S4 (1,4,7,10-tetrathiacyclododecane), 9S3 (1,4,7-trithiacyclononane),
16S4 (1,5,9,13-tetrathiacyclohexadecane), [Pt(NCPh)2Cl2] (bis(benzonitrile)dichloro
platinum(II)), [Pd(NCPh)2Cl2] (bis(benzonitrile)dichloro palladium(II)), pyr (1,4pyrazine), bipy (4,4’-bipyridine), bpe (1,2-bis(4-pyridyl) ethane), tpp (tetra-(2-pyridyl)
pyrazine), dcn (1,4-dicyanobenzene), fum (fumaronitrile), 4,7-phen (4,7phenanthroline), pmd (pyrimidine), 5,6-dm-phen (5,6-dimethyl, 1,10-phenanthroline),
4,7-dm-phen (4,7-dimethyl, 1,10-phenanthroline), 4,7-dph-phen (4,7-diphenyl, 1,10phenanthroline), 5-nitro-phen (5-nitro, 1,10 phenanthroline), 2,2’-biquinoline, TlPF6
(thallium hexafluorophosphate), NH4PF6 (ammonium hexafluorophosphate), AgOTf
(silver triflate), AgPF6 (silver hexafluorophosphate), AgNO3 (silver nitrate), and
AgCF3SO3 (silver trifluoromethanesulfonate), were purchased and used as received.
All solvents were used as received. The dried acetone was prepared by placing acetone
in a flask with drierite, which is made of anhydrous calcium sulfate. Drierite was added
to the solvent until the drierite pieces no longer stuck together. The complex
[{Ru(12S4)MeCN}2(μ-bipy)](PF6)4 was previously prepared in our group.
Caution! Thallium salts used in this report are highly toxic and should be
handled with care; use of gloves is essential. All thallium salts must be disposed off in
properly labeled vials. Diethyl ether is a highly flammable liquid; precautionary
32
measures must be taken to ensure that it is not used near open flames. Chloroform is a
carcinogen and should be handled using gloves and under a hood to avoid exposure to
harmful vapors. Dimethyl sulfoxide is a skin soluble liquid that readily dissolves other
liquids or complexes mentioned in this report. Special care must be taken when
handling this solvent because anything that it dissolves can be absorbed through the
skin and introduced within the human body; use of gloves is of utmost importance.
Ammonia is a volatile liquid that aggravates the nasal and ocular cavities, it should be
used in the hood to avoid exposure to the harmful fumes.
Measurements:
Elemental Analyses were performed by Atlantic Microlab, Atlanta, GA. 1H,
13
C, 13C DEPT, 31P NMR, and 19F NMR spectra were obtained through JEOL ECX-
400 MHz NMR spectrometer using CD3NO2, CD3CN, CD3OD, CDCl3, for both
deuterium lock and reference. The 195Pt NMR spectra were obtained using aqueous
solutions of [PtCl6]2- (0 ppm) as an external reference and delay time of 1.0 second. 13C
DEPT NMR was performed at a selection angle of 135°, which produced methine and
methyl peaks in phase while methylene peaks were 180° out of phase to the methyl and
methine peaks. Infrared spectra were obtained on a Nicolet FT-IR using dry preweighed KBr powder and an ATR accessory. UV-Visible spectra were obtained via the
Cary 100 UV/Vis spectrophotometer and the Varian 100 UV/Vis spectrophotometer.
Crystal structures were obtained by Dr. Don VanDerveer at Clemson University in
Clemson, SC.
33
Procedures:
I. Ruthenium (II) Chemistry
A. 12S4 (1,4,7,10-tetrathiacyclododecane) Chemistry
1. Corner Formation, Preparation of [Ru(12S4)(dmso)Cl]+
A1-1. Preparation of cis-[Ru(12S4)(dmso)Cl]Cl
A mixture of [Ru(dmso)4Cl2] (856.7 mg, 1.768 mmol) and 12S4 (425.2 mg,
1.768 mmol) was placed in a 50 mL flask. To this mixture was added 25 mL absolute
ethanol. The reaction was refluxed for 4 hours under N2 for 15 minutes, and the
solution color changed from pale to bright yellow. The solution was then cooled to
room temperature. A volume of 10 mL ether was added to the solution, and the
solution was cooled overnight in a refrigerator. The yellow solid was filtered and
washed with 15 mL ether to yield 859.4 mg (99.1%) of yellow crystals of cis[Ru(12S4)(dmso)Cl]Cl.
A1-2. Preparation of cis-[Ru(12S4)(dmso)Cl]PF6
A mass of [Ru(12S4)(dmso)Cl]Cl (880.5 mg, 1.795 mmol) was added to 100
mL of water in a 250 mL flask. The mixture was stirred until all of the complex
dissolved, which took 5 minutes. To this solution was added an excess of NH4PF6
(877.7 mg, 5.384 mmol). The NH4PF6 went into solution by manual swirling, and
further swirling for 3 minutes allowed for the final product to precipitate from solution.
The reaction was refrigerated overnight. The bright yellow product was filtered and
washed with 3 x 5 mL of water yielding 932.0 mg (86.54%) of cis[Ru(12S4)(dmso)Cl]PF6.
34
2. Dechlorination of [Ru(12S4)(dmso)Cl](PF6)
A2-1. Thallium hexafluorophosphate dechlorination of cis-[Ru(12S4)(dmso)Cl]PF6
A mixture of [Ru(12S4)(dmso)Cl]PF6 (465.0 mg, 0.7749 mmol), TlPF6 (270.7
mg, 0.7749 mmol), and H2O (13.95 μL, 0.7749 mmol) were added to 20 mL dried
acetone in a 50 mL flask. The mixture in the 50 mL flask was refluxed for 5 hours. The
reaction was filtered, rotary evaporated to dryness and then dissolved in MeOH,
because the TlCl product was insoluble in MeOH. The solution was filtered, yielding
253 mg, 136.8%, of white, insoluble TlCl solid. The filtered solution was rotary
evaporated to saturation, and a volume of 10 mL of ether was added drop wise to
precipitate the ruthenium complex from solution. The reaction was refrigerated
overnight yielding 326 mg (57.8%) of cis-[Ru(12S4)(dmso)(H2O)]PF6. IR (KBr, cm-1)
2987.42, 2968.23, 2929.85, 1621.06, 1421.48, 1294.82, 1087.56 (s, dmso), 1037.67,
968.58, 926.36 (s, dmso), 841.92 (s, PF6-), 722.94, 692.24, 557.91 (s, PF6-), 481.14,
427.41. 1H NMR (CD3NO2, ppm) 12S4 and dmso: 4.18-4.13 (m, 4 H), 3.65 (d, 2 H),
3.61 (d, 2 H), 3.58 (s, 1 H), 3.57(d, 1 H), 3.55 (d, 1 H), 3.54 (d, 1 H), 3.52 (s, 1 H),
3.50 (s, 1 H), 3.43 (d, 1 H), 3.42 (d, 1 H), 3.40 (d, 1 H), 3.39 (d, 1 H), 3.36 (s, 1 H),
3.35 (s, 1 H), 3.346 (s, 2 H), 3.34 (s, 1 H), 3.33 (s, 1 H), 3.287 (s, 12 H), 3.25 (s, 1 H),
3.13 (d, 2 H), 3.095 (d, 2 H), 3.08 (s, 1 H), 3.07 (s, 1 H), 3.06 (d, 2 H), 3.04 (s, 2 H),
3.02 (d, 2 H), 2.99 (d, 2 H), 2.96 (d, 2 H), 2.92 (d, 2 H), 2.12 (b, 5H). 13C DEPT NMR
(CD3NO2, ppm) 12S4 and dmso: 46.87 (2 C), 45.97 (2 C), 42.37 (1 C, dmso), 34.32 (2
C), 34.04 (2 C).
35
A2-2. Isolation of cis-[Ru(12S4)(dmso)(H2O)](PF6)2 from silver nitrate
dechlorination
This experiment is a modification of a literature dechlorination procedure.24
A mixture of [Ru(12S4)(dmso)Cl]PF6 (238 mg, 0.397 mmol) and AgNO3 (67.4
mg, 0.397 mmol) was added to a 50 mL flask. To this was added 30 mL of a
water/ethanol mixture (1:1). The flask was then covered with aluminum foil, purged
with N2 for 15 minutes, and then refluxed for 2 hours, under N2. The precipitated AgCl
was filtered from the reaction. After the reaction cooled for one hour, the supernatant
with the dechlorinated Ru complex was centrifuged for 5 minutes to separate any
unfiltered AgCl from solution. The final yield of AgCl was 49.1 mg (86.4%) of white
solid. The solution was then transferred to a 50 mL flask, and an excess of NH4PF6
(129 mg, 0.793 mmol) was added to the solution. The solution was manually stirred
until all of the NH4PF6 dissolved. The solution was refrigerated for 2 days. The original
contents were a clear yellow solution, but after two days a yellow crystalline solid
formed. The crystalline solid was filtered and washed with 2 x 5 mL of ether followed
by 2 x 3 mL of H2O. The final product was 218 mg (75.6%) of cis[Ru(12S4)(dmso)(H2O)](PF6)2 as a yellow solid. C10H26F12O3P2RuS5 (745.64): calcd.
C 16.11, H 3.51, S 21.50, Cl 0.00; found C 16.40, H 3.48, S 21.66, Cl 0.00. IR (KBr,
cm-1) 3063.09 (b), 2454.22 (b), 1647.22 (b), 1418.03 (s), 1269.54 (s), 1082.32 (s,
dmso), 1020.98 (s), 840.22 (s, PF6-). 1H NMR (CD3NO2, ppm) δ: 5.582 (s, 0.975H,
_______________________
Thomas, Jim A.; Brammer, Lee; Adams, harry; Hawxwell, Samuel M.; Shan, Naz.
“Self-Assembly of Electroactive Thiacrown Ruthenium(II) Complexes into HydrogenBonded Chain and Tape Networks.” Inorg. Chem. 2008, 47, 11551-11560.
24
36
H2O), 5.253 (bs, 0.0748H, H2O), 4.205-4.300 (m, 1.35H, 12S4), 3.344-3.4891 (m,
7.02H, 12S4), 3.308 (s, 3.35H, dmso), 3.212-3.283 (m, 1.62H, 12S4), 3.199 (s, 1.43H,
dmso), 2.709-3.168 (m, 6.01H, 12S4), 2.375 (s, 10.4H, dmso). 13C NMR (CD3NO2,
ppm) δ: 46.03 (major dmso), 45.76 (minor dmso), 44.28 (major 12S4), 43.79 (minor
12S4), 42.61 (minor 12S4), 42.41 (major 12S4), 35.06 (major and minor 12S4), 34.70
(minor 12S4), 33.88 (major 12S4). 31P NMR (CD3NO2, ppm) δ: -144.108 (hept, PF6-).
19
F NMR (CD3NO2, ppm) δ: -73.230 (d, PF6-).
A2-3. Silver triflate dechlorination of [Ru(12S4)(dmso)Cl]PF6
This experiment is a modification of a literature dechlorination procedure.25
A mixture of [Ru(12S4)(dmso)Cl]PF6 (309.5 mg, 0.5158 mmol) and AgCF3SO3
(132.5 mg, 0.5158 mmol) was added to a 50 mL flask. To this was added 20 mL of
EtOH and a stoichiometric excess of dmso (0.6594 mL, 9.284 mmol). The reaction was
protected from light by aluminum foil and refluxed for 2 hours under N2. The white
AgCl was removed by filtering through a fine frit., yielding 65.8 mg (89.0%) of white
solid. To the yellow supernatant was added 5 mL of water, and the solution was
refrigerated for 5 days. The solution was rotary evaporated to oil and re-dissolved in 5
mL of acetone. Ether was added dropwise until a yellow solid began to precipitate.
They yellow solid was filtered yielding 199 mg (52.8%) of cis[Ru(12S4)(dmso)(H2O)](PF6)(CF3SO3). C11H24F9O5PRuS6 (731.72) calc. Cl 0.00;
______________________
Zangrando, Alessio E.; Munini, Fabio; Baiutti, Edi; Zangrando, Ennio; Iengo,
Elisabetta. “Synthesis and Structural and Spectroscopic Characterization of New RuIIdmso Precursors with Face-Capping Ligands for Use in Self-Assembly Reactions.”
Eur. J. Inorg. Chem. 2005, 1027.
25
37
found Cl trace: < 0.25. 1H NMR (D2O, ppm) δ: 4.079-4.129 (dd, 2.00 H, 12S4), 3.5933.640 (dd, 1.99 H, 12S4), 3.364-3.417 (dd, 2.00 H, 12S4), 3.305-3.353 (dd, 2.00 H,
12S4), 3.287 (s, 0.204 H), 3.256 (s, 6.00 H, dmso-O), 3.082-3.171 (td, 2.04 H, 12S4),
2.980-3.058 (td, 2.01 H, 12S4), 2.810-2.898 (td, 2.01 H, 12S4), 2.708-2.790 (dt, 2.00
H, 12S4), 2.626 (s, 3.49 H, free dmso). 13C NMR (D2O, ppm) δ: 119.73 (q, CF3SO3);
44.65 (dmso-O), 43.03 (2 C, 12S4), 40.62 (2 C, 12S4), 38.81 (free dmso), 33.38 (2 C,
12S4), 32.22 (2 C, 12S4). 19F NMR (D2O, ppm) δ: -71.739 (d, PF6-); -78.638 (s,
CF3SO3-).
3. Self-assembly Reactions to Prepare Molecular Squares
A3-1. Attempted square preparation: [{Ru(12S4)MeCN}2-μ-bipy](PF6)4 + bipy
A mixture of [{Ru(12S4)MeCN}2-μ-bipy](PF6)4 (93.45 mg, 0.06400 mmol)
and bipy (10.0 mg, 0.0640 mmol) was added to 5 mL of CH3NO2 in a 25 mL flask. A
drop of water was added to the reaction to help facilitate the reaction. The solution was
refluxed for 7 hours, and there was no color change. NMR showed the presence of
coordinated MeCN peaks and a complex bipy area. 13C NMR (CD3NO2, ppm) δ: bipy:
156.70, 156.47, 151.58, 150.56, CH3CN: 125.06, 123.49, 122.97; 12S4: 44.94, 41.94,
36.64, 34.301.
A3-2. Attempted square preparation: [Ru(12S4)(dmso)Cl]PF6 + bipy
This experiment is based upon a literature report of a bridged complex.14
A mass of [Ru(12S4)(dmso)Cl]PF6 (200 mg, 3.33 mmol) was added to a 100
mL flask containing 10 mL of ethanol and 10 mL of water. The flask was covered in
Al foil to eliminate light. The solution was refluxed under nitrogen. Upon reflux, a
38
stoichiometric 1.3 x excess of AgNO3 (73.6 mg, 4.33 mmol) was added to the solution.
Some solution was lost due to vigorous reflux upon addition of AgNO3. The mixture
was flushed with nitrogen and refluxed for 4 hours. After refluxing, the solution was
orange with black AgCl on the bottom of the flask. The AgCl was filtered and washed
with 5 mL of water and 5 mL of ethanol. The filter flask was covered with Al to
decrease photodecomposition of Ag. The supernatant was poured into a reaction flask.
To this was added bipy (52.1 mg, 3.33 mmol), and the solution was refluxed for 3
hours. After refluxing, the solution was cooled to room temperature. Once cooled, a 5fold excess of NH4PF6 (271.6 mg, 16.65 mmol) was added to the solution. The solution
was rotary evaporated until 10 mL of solution remained. The solution was refrigerated
overnight. The following day a yellow precipitate was present along with an orange
solution. The yellow precipitate was filtered and washed with 3 mL of ethanol and 2 x
5 mL of ether. The total yield of precipitate was 125 mg (47.8%). The complex was
soluble in nitromethane, acetonitrile, and a 1:1 methanol and distilled water mixture.
FT-IR was run on the crude product to confirm the presence of PF6-. A mass of 20 mg
of the complex was dissolved in CD3NO2, although some precipitated out of solution
over time. The solution was centrifuged, the supernatant was placed in an NMR tube
and analyzed by NMR. The 1H NMR showed multiple species present in the solution.
The complex was dissolved in 1 mL of CH3CN in a crystallization tube. The tube was
placed in an ether diffusion chamber. An orange film formed overnight along the walls
of the crystallization tube. The supernatant was removed, the orange film was isolated
and dried and then redissolved in CD3CN. The orange solution was analyzed by NMR.
39
1
H NMR (CD3NO2, ppm): δ: bipy: 8.833-8.538 (m, 3.39 H), 7.874-7.706 (m, 3.36 H);
4.348-2.333 (m, 16.0 H, 12S4), 2.151 (t, 91.72, free dmso).
A3-3. Attempted square preparation: [Ru(12S4)(dmso)Cl]Cl + bipy
This experiment is based upon a literature report of a molecular cube
[Ru8(9S3)8bipy12](Cl)16.10
A mixture of [Ru(12S4)(dmso)Cl]Cl (9.81 mg, 0.200 mmol) and bipy (3.12 mg,
0.200 mmol) was placed in an NMR tube by being dissolved in 1 mL of CD3NO2. The
reaction was monitored by 1H NMR for a week. Some self-assembly was observed
because of the change in the bipy spectrum. However, no further changed occurred
after a month of monitoring. 1H NMR (CD3NO2, ppm): δ: bipy: 8.846 (dd, 1.61 H),
8.724 (dd, 1.65 H), 7.820-7.731 (m, 3.21 H); 12S4: 4.179-4.101 (m, 2.07 H), 3.6993.610 (d, 1.85 H), 3.518-3.433 (m, 2.05 H), 3.433-3.306 (m, 1.98 H), 3.306-3.154 (s,
1.98 H), 3.152-3.031 (m, 2.04 H), 3.031-3.004 (s, 2.04 H), 3.004-2.917 (m, 2.0 H);
2.516 (t, 4.96 H, dmso), 2.395 (s, 12.03 H, free dmso).
The same experiment was performed in a different solvent. A mixture of
[Ru(12S4)(DMSO)Cl]Cl (9.81 mg, 0.200 mmol) and bipy (3.12 mg, 0.200 mmol) was
dissolved in CD3CN and placed in an NMR tube. However, there was no change in the
1
H NMR spectrum over a month of analysis. 1H NMR (CD3NO2, ppm): δ: bipy: 8.833-
8.538 (m, 3.39 H), 7.874-7.706 (m, 3.36 H); 4.348-2.333 (m, 16.0 H, 12S4), 2.151 (t,
91.72, free dmso).
40
A3-4. Attempted square preparation: [Ru(12S4)(dmso)(H2O)](PF6)2 + bipy
A mixture of [Ru(12S4)(dmso)(H2O)](PF6)2 (80.0 mg, 0.110 mmol) and bipy
(17.2 mg, 0.110 mmol) was added to 10 mL of CH3OH/H2O mixture (1:1) in a 25 mL
flask. The solution was refluxed for 5.5 hours under N2. It was rotary evaporated to
saturation (a volume of 1 mL) and then refrigerated. The
[Ru(12S4)(dmso)(H2O)](PF6)2 complex used contained impurities, and did not react as
expected. The problem was confirmed by washing the product of the reaction with
CHCl3, which removed excess bipy. A mass of 7.0 mg (41%) of the bipy used in the
reaction was recovered.
A cleaner sample of [Ru(12S4)(dmso)(H2O)](PF6)2 was used for the second
attempt.
A mixture of pure [Ru(12S4)(dmso)(H2O)](PF6)2 (30.0 mg, 0.0412 mmol) and
bipy (6.44 mg, 0.0412 mmol) was added to 10 mL of a CH3OH/H2O mixture (1:1) in a
25 mL flask. The solution was refluxed for 6 hours under N2. The color changed from a
bright yellow color to a tan yellow color. Upon cooling, the solution was rotary
evaporated to saturation, a volume of 1 mL, and then refrigeration overnight. The final
product was 20.0 mg (61.5%) of tan solid, and there was no presence of free bipy. 1H
NMR (CD3NO2, ppm) bipy: 8.89-8.71 (m, 4 H), 7.79-7.73 (m, 4 H), 12S4: 4.18-4.11
(m, 4 H), 3.66-3.60 (m, 4 H), 3.51-3.40 (m, 8 H), 3.31-3.24 (m, 4 H), 3.08-2.92 (m, 12
H); H2O: 2.14 (s, 16 H). 13C NMR (CD3NO2, ppm) bipy: 157.23, 157.06, 123.96,
123.89; 12S4: 45.68, 42.06, 34.75, 34.37.
41
A3-5. Attempted square preparation, using Thomas’s Reaction:
[Ru(12S4)(dmso)Cl]PF6 + bipy, after silver nitrate dechlorination
This experiment is a modification of a literature dechlorination procedure.24
A mixture of [Ru(12S4)(dmso)Cl]PF6 (300 mg, 0.498 mmol) and AgNO3 (86.7
mg, 0.498 mmol) was added to a 50 mL flask. To this was added 30 mL of a
water/ethanol mixture (1:1). The reaction flask was covered with Al foil and purged
with nitrogen for 15 minutes, and a very slow flow was kept throughout the reaction.
The reaction was refluxed for 2 hours. After the flask cooled to room temperature, a
mass of 60.5 mg (84.7%) of white AgCl was filtered and washed with 5 mL of ethanol
and 5 mL of water. The supernatant that contained the yellow ruthenium complex was
poured into a flask, capped, parafilmed and left to see if more AgCl would precipitate.
The mixture was left for 6 days, but no AgCl precipitated. To the solution was added
bipy (77.8 mg, 0.498 mmol). The reaction was flushed with nitrogen for 15 minutes
and refluxed for 2.3 hours with nitrogen on a slow flow. The reaction was allowed to
cool to room temperature overnight. The next day a solid was found at the bottom of
the reaction flask. The reaction was filtered and washed with 2 x 3 mL of water/ethanol
(1:1). The orange mother liquor was added to a 100 mL flask, along with a mass of
NH4PF6 (162.5 mg, 0.997 mmol). This solution was flushed with N2 and refluxed for
10 minutes. The reaction was cooled and then rotary evaporated to one half its original
volume. The reaction was refrigerated for 6 days. Orange crystals formed on the
bottom of the flask. The orange solid was filtered and washed with 3 x 5 mL of ether.
This yielded 313.4 mg (79.85%) of orange solid. The orange solid was purified through
42
crystallization in an ether diffusion chamber. For the crystallization, nitromethane was
used at first and then the solvent that dissolved the complex was switched to
acetonitrile. Orange crystals were isolated from the crystallization tube and dissolved in
CD3NO2. The sample was analyzed by NMR. 1H NMR (CD3NO2, ppm): δ: bipy: 8.993
(dd, 0.428 H), 8.765 (dd, 2.0 H), 8.720-8.756 (dd, 1.18 H), 8.022 (bd, 0.213 H), 7.890
(dd, 1.982 H), 7.851-7.864 (dd, 0.839 H), 7.721-7.819 (m, 1.366 H), 12S4: 4.305 (m,
1.944 H), 3.731-3.866 (m, 3.114 H), 3.496-3.4614 (m, 6.774 H), 3.169-3.313 (m, 2.063
H), 3.060-3.130 (m, 8.047 H), 2.878-2.993 (m, 2.785 H); 3.435 (q, 0.212 H, ether),
2.476 (s, 2.8 H, dmso), 2.442 (s, 0.672 H, dmso), 2.196 (s, 14.59 H, water), 2.096 (s,
4.301 H, acetone), 1.999 (s, 2.321 H, acetonitrile), 1.180 (t, 0.286 H, ether). 13C NMR
(CD3NO2, ppm) δ: bipy: 156.73, 146.94, 125.09; 12S4 and dmso: 45.00, 41.98, 36.69,
34.45, 30.79.
A3-6. Attempted square preparation: [Ru(12S4)(dmso)(H2O)](PF6)2 + bipy
A mixture of [Ru(12S4)(dmso)(H2O)](PF6)2 (95.4 mg, 0.131 mmol) and bipy
(20.5 mg, 0.131 mmol) was added to an Al covered 50 mL flask. To this was added 15
mL of MeOH. The reaction was flushed with nitrogen for 10 minutes, and then
refluxed for 30 minutes at which point a solid began to form. A volume of 8 mL of
MeNO2 was added to dissolve the solid. The reaction refluxed for an additional 30
minutes and then cooled to room temperature. A volume of 20 mL of ether was added
to the solution, and the solution was refrigerated overnight. A small solid product was
filtered and washed with 3 x 5 mL of ether. The filtered, yellow complex was
redissolved in a mixture of 8 mL of H2O, 2 mL of EtOH and 15 mL of MeOH. The
43
above reflux procedure was repeated in this new solvent system. The reason for this is
that there was not color change present from before and after the reaction. The product
of this reflux was rotary evaporated to saturation, a volume of 4 mL, and an orange
solid precipitated from solution. The orange solid was filtered, washed with 3 x 5 mL
of ether, and collected. This yielded 57.2 mg (25.2%) of orange [{Ru(12S4)(bipy)}2(μbipy)](PF6)4 solid. The orange solid was dissolved in nitromethane and put to
crystallize in an ether diffusion chamber. The red oil that was obtained was used for
NMR. 1H NMR (CD3NO2, ppm) δ: bipy: 9.0151-8.5397 (m, 6.439 H), 7.910-7.537 (m,
6.555 H); 4.173-3.521 (m, 7.014 H, 12S4), 3.429 (q, 9.955 H, ether), 3.333-2.925 (m,
8.986 H, 12S4), 2.472 (s, 2.642 H), 1.119 (t, 13.76 H, ether). 19F NMR (CD3NO2, ppm)
δ: -73.106 (d, PF6-).
The results of the above experiment indicate that there were three bipy present
for every two 12S4. This pointed towards a bipy bridged ruthenium corners that had
bipy on them. This was not the desired self-assembled product so a stoichiometric
amount of bipy and Ru(12S4) was added to the product of the above reaction and
refluxed.
A mixture of [{Ru(12S4)(bipy)}2(μ-bipy)](PF6)4 (55.5 mg, 0.0321 mmol),
[Ru(12S4)(dmso)(H2O)](PF6)2 (46.6mg, 0.0641 mmol), and bipy (5.006 mg, 0.03205
mmol) was added to a 50 mL flask. To this was added 7.5 mL of MeOH and 5 mL of
H2O. The reaction was purged with nitrogen for 30 minutes, and then refluxed for 24
hours. The reaction was flushed with nitrogen as it cooled for 30 minutes following the
reflux. The reaction produced an orange-golden solution with brown-black solids
44
present in small amount around the flask. This dark solid is believed to originate from
AgCl that was not cleaned from the [Ru(12S4)(dmso)(H2O)](PF6)2 used in this
reaction. The supernatant was decanted and filtered using filter paper, thereby
removing the black solid from the solution. The supernatant was rotary evaporated to
dryness. The solid was filtered and washed with 2 x 3 mL of water, then 3 x 5 mL of
CHCl3. The chloroform washing was allowed to dry and showed no free bipy. The
orange solid was insoluble in water and chloroform. It was isolated as 71.4 mg of
sample and redissolved in CD3NO2 to be examined by NMR. 1H NMR (CD3NO2, ppm)
δ: 9.022-7.488 (m, 8 H, bipy), 4.13q-2.432 (m, 19.88 H, 12S4), 2.096 (s, 4.19 H,
H2O).
A3-7. Attempted square preparation: [Ru(12S4)(dmso)(H2O)](PF6)2 + pyr
Attempt 1: A mixture of [Ru(12S4)(dmso)(H2O)](PF6)2 (18.9 mg, 0.0260
mmol) and pyr (2.08 mg, 0.0260 mmol) was added to a solution of 10 drops D2O and
10 drops CD3OD in a 5 mL reaction flask. The reaction was refluxed for 2 hours under
nitrogen. The product was 9.0 mg (49%) of red solid that was dissolved in CD3NO2, but
not in CD3CN. The supernatant from the reaction was also examined.
The reaction was attempted on a larger scale and was examined through NMR
again.
Attempt 2: A mixture of [Ru(12S4)(dmso)(H2O)](PF6)2 (80.0 mg, 0.110 mmol)
and pyr (8.81 mg, 0.110 mmol) was added to a 10 mL MeOH/H2O mixture (1:1) in a
25 mL flask. The solution was refluxed for 4.5 hours under N2, and then cooled to
room temperature. The complex began to crystallize out of the solvent as it cooled. The
45
reaction was refrigerated for 24 hours. The reaction was filtered and rinsed with 5 mL
of a cold MeOH/H2O mixture (1:1). The yield was 38 mg (49%) of an orange solid. IR
(KBr, cm-1) 1638.24, 1421.71, 840.27 (PF6), 559.39 (PF6). 1H NMR (CD3NO2, ppm)
pyr: 8.74 (d, 2 H), 8.68 (s, 4 H), 8.577 (bs, 2 H), 12S4: 4.19-4.10 (m, 8 H), 3.66-3.59
(d, 8 H), 3.50-3.39 (m, 16 H), 3.34-3.26 (m, 8 H), 3.10-2.92 (m, 32 H). 13C NMR
(CD3NO2, ppm) pyr: 151.7 (4 C), 151.3 (2 C), 147.3 (2 C), 12S4: 45.70 (2 C), 45.65 (2
C), 42.18 (2 C), 42.03 (2 C), 35.14 (2 C), 34.92 (2 C), 34.57 (2 C), 34.41 (2 C).
A3-8. Attempted square preparation: [Ru(12S4)(dmso)Cl]PF6 + dcn, after silver
nitrate dechlorination
This experiment is a modification of a literature dechlorination procedure.24
A mixture of [Ru(12S4)(dmso)Cl]PF6 (75.0 mg, 0.125 mmol) and AgNO3 (21.2
mg, 0.125 mmol) was added to a 25 mL flask. To this was added 8 mL of a
water/ethanol mixture (1:1). The reaction flask was covered with Al foil, purged with
nitrogen for 15 minutes, and a very slow flow was maintained throughout the reflux.
The reaction was refluxed for 2 hours, then cooled to room temperature. After one hour
in the refrigerator, grey colored AgCl (photodecomposed product) precipitated from
solution. The AgCl was filtered from solution yielding 11.2 mg (62.6%) of expected
product. The supernatant with the dechlorinated ruthenium complex was poured into a
25 mL flask. To this was added a mass of dcn (16.0 mg, 0.125 mmol). The flask was
covered by Al foil, and the reaction was stirred overnight using a magnetic stirrer.
However, there was no change in the reaction because the solution remained yellow in
color . The reaction was flushed with N2 for 15 minutes and refluxed for 2 hours under
46
a slow flow of N2. The product was filtered, and the vibrant yellow solution was
transferred to a 25 mL flask. To this was added a mass of NH4PF6 (40.7 mg, 0.250
mmol), and the reaction was refluxed for one hour. The solution was rotary evaporated
to saturation, a volume of 4 mL, and then refrigerated overnight. The solid was filtered,
washed with 3 mL of ethanol and 2 x 5 mL of ether. This yielded 21.5 mg (21.1%) of
yellow solid.
A3-9. Attempted square preparation: [Ru(12S4)(dmso)Cl]PF6 + bpe, after silver
nitrate dechlorination
This experiment is a modification of a literature dechlorination procedure.24
A mixture of [Ru(12S4)(dmso)Cl]PF6 (75mg, 0.125mmol) and AgNO3
(21.2mg, 0.125mmol) was added to a 25 mL flask. To this was added 8 mL of a
water/ethanol mixture (1:1). The reaction flask was covered with Al foil, purged with
nitrogen for 15 minutes, and a very slow flow was maintained throughout the reflux.
The reaction was refluxed for 2 hours, then cooled to room temperature. After one hour
in the refrigerator, black AgCl was filtered from the reaction yielding 14.2 mg (79.3%)
of AgCl. The supernatant with the dechlorinated ruthenium complex was poured into a
25 mL flask. To this was added bpe (23.0 mg, 0.125 mmol). The flask was covered by
Al foil and the reaction was stirred overnight using a magnetic stirrer. However, there
was no change in the reaction because the solution remained yellow in color. The
reaction was flushed with N2 for 15 minutes and refluxed for 2 hours under a slow flow
of N2. The product was filtered and the clear yellow solution was transferred to a 25
mL flask. To this was added a mass of NH4PF6 (40.7 mg, 0.250 mmol), and the
47
reaction was refluxed for one hour. The solution was rotary evaporated to saturation,
refrigerated overnight, and a solid precipitated from solution. The solid was filtered
and washed with 2 x 5 mL of ether. This yielded 81.2mg (79.7%) of
[Ru(12S4)(bpe)(H2O)](PF6)2 as an orange solid. IR (KBr, cm-1) 2360.40, 1617.78,
1507.87, 1421.73, 1267.26, 1222.70, 1062.30, 839.51 (PF6-), 735.55, 661.28 (PF6-). 1H
NMR (CD3NO2, ppm) δ: bpe: 8.675-7.146 (m, 7.962 H), 8.558 (t, 2.0 H), 8.264 (t, 2.0
H), 7.343 (dd, 2.0 H), 7.172 (dd, 2.0 H); 12S4 and bpe: 4.289-2.912 (m, 20 H); 2.151
(s, 6.0 H, H2O). 13C NMR (CD3NO2, ppm) δ: bpe: 156.06, 155.56, 154.57, 128.67,
127.98, 127.61, 44.74, 37.44; 12S4: 44.26, 41.58, 34.56, 33.52. 19F NMR (CD3NO2,
ppm) δ: -73.245 (d, PF6-).
31
P NMR (CD3NO2, ppm) δ: -144.08 (hept, PF6-).
A3-10. Attempted square preparation: [Ru(12S4)(dmso)(H2O)](PF6)2 + fum
A mass of [Ru(12S4)(dmso)(H2O)](PF6)2 (94.0 mg, 0.129 mmol) and fum (10.9
mg, 0.129 mmol) was added to a 50 mL flask. To this was added 15 mL of MeOH. The
mixture was refluxed for 20 minutes until a red solid formed. A volume of 2 mL of
EtOH and then 8 mL of H2O was added (only H2O dissolved the red solid) to the
reaction. The solution turned orange and 15 minutes later it became red. Additional
refluxing resulted in a darkening of the red color. The reflux was stopped at a total time
of 45 minutes and then flushed with N2. The contents were transferred to a 100 mL
flask, and 20 mL of ether were added but no precipitate formed. The solution was
rotary evaporated to saturation, a volume of 1 mL, and a red solid began to precipitate.
A volume of 5 mL of ether was added but no precipitate formed. The reaction was
refrigerated overnight. A brown solid would form in the red solution. The contents of
48
the flask were rotary evaporated to dryness, dissolved in acetone, placed in a
crystallization tube, and allowed to crystallize in an ether diffusion chamber. A red oil
was isolated, rotary evaporated to dryness, dissolved in 1 mL of deuterated acetone,
and examined by NMR. 1H NMR (CD3COCD3, ppm) δ: fum: 7.418-6.487 (m, 0.75 H,
fum), 4.416 (s, 1.19 H); 3.943-3.247 (m, 12.13 H, 12S4), 3.219 (s, 1.58 H), 3.1702.649 (m, 3.87 H), 2.581 (s, 6.47 H). 31P (CD3COCD3, ppm) δ: -143.679 (hept, PF6-).
19
F NMR (CD3COCD3, ppm) δ: -72.262 (s, PF6-).
4. Synthesis of Novel Binuclear Ru(12S4) Complexes
A4-1. Preparation of [{Ru(12S4)Cl}2-μ-pyr](PF6)2
A mass of [Ru(12S4)(dmso)Cl]Cl (150.0 mg, 0.3058 mmol) was added to 15
mL of EtOH in a 50 mL flask. The resulting yellow cloudy solution was stirred under
N2 until the entire complex had dissolved. To this solution a mass of pyrazine (12.25
mg, 0.1528 mmol) was added. The solution was refluxed under N2 for 3 hours and then
stirred at room temperature for an additional 3 hours. A mass of NH4PF6 (49.845 mg,
0.30576 mmol) was added to the solution, and an orange precipitate formed instantly.
The solution was chilled for 24 hours to complete precipitation. The solid was filtered
and washed with 3 x 5 ml of ether. The product was an orange crystalline solid 171.8
mg (91.40%) of [{Ru(12S4)}2-μ-pyr](PF6)2.The final product had some solubility in
CH3NO2 but was completely soluble in CH3CN. IR (KBr, cm-1) 2995.45, 2935.09,
1585.63, 1482.16, 1413.17, 1314.01, 1292.46, 1089.82, 1029.46, 1003.59, 930.30,
839.76(PF6-), 559.52 (PF6-). 1H NMR (CD3CN, ppm) pyr: 8.67 (d, 2 H), 8.58 (s, 2 H),
8.55 (d, 2 H), 12S4: 4.06-4.03 (m, 4 H), 4.03-3.99 (m, 4 H), 3.54-3.24 (m, 28 H), 3.23
49
(s, 8 H), 3.22-316 (m, 4 H), H2O: 2.17 (s, 8 H). 13C NMR (CD3CN, ppm) pyr: 151.34
(4 C), 150.88 (2 C), 146.78 (2 C), 12S4: 46.72 (2 C), 45.43 (2 C), 45.07 (2 C), 41.69 (2
C), 41.52 (2 C), 41.40 (2 C), 34.63 (2 C), 34.43 (2 C), 34.25 (2 C), 34.08 (2 C), 33.96
(2 C), 33.52 (2 C).
A4-2. Attempted Preparation of cis-[Ru(12S4)(pyr)Cl]PF6
A mass of [Ru(12S4)(dmso)Cl]Cl (75.0 mg, 0.153 mmol) was added to 10 mL
of a MeOH/H2O mixture (1:1), and the solution was stirred until all of the complex
dissolved. A mass of pyrazine (12.2 mg, 0.153 mmol) was added. The reaction was
refluxed under N2 for 19 hours. A mass of NH4PF6 (24.9 mg, 0.153 mmol) was added
to the reaction, and an orange solid formed. The solution was rotary evaporated to
saturation and refrigerated overnight. The orange solid was filtered and washed with 2
x 3 mL of ethanol and then 3 x 5 mL of ether. The final product yielded 75.0 mg
(81.5%) of solid complex. The solid was set to crystallize in an ether diffusion chamber
by being dissolved in CH3NO2. Two different crystals formed: red and orange. These
were hand separated and analyzed, because they resembled two distinct Ru complexes.
The following are the results for the red crystals: IR (KBr, cm-1) 2989.4,
2950.6, 1611.5, 1426.2, 1302.1, 1097.2, 1019.4, 930.1, 838.4(PF6-), 699.2, 559.6 (PF6). 1H NMR (CD3NO2, ppm) pyr: 8.74 (d, 2 H), 8.68 (s, 4 H), 8.58 (bs, 2 H), 12S4: 4.194.11 (m, 8 H), 3.66-3.59 (m, 8 H), 3.56-3.38 (m, 16 H), 3.37 (m, 16 H), 3.11-2.90 (m,
24 H), H2O: 2.10 (s, 20 H). 13C NMR (CD3NO2, ppm) pyr: 151.729 (4 C), 151.338 (2
C), 147.315 (2 C), 12S4: 46.887 (2 C), 45.971 (2 C), 45.752 (2 C), 45.685 (2 C),
50
42.367 (2 C), 42.205 (2 C), 42.062 (2 C), 35.150 (2 C), 34.930 (2 C), 34.597 (2 C),
34.425 (2 C), 34.311 (2 C), 34.034 (2 C).
The following are the results for the orange crystals: IR (KBr, cm-1) 2994.3,
2956.5, 1591.5, 1541.3, 1426.4, 1311.8, 1085.2, 1023.0, 930.5, 839.1 (PF6-), 701.7,
562.5 (PF6-). 1H NMR (CD3NO2, ppm) pyr: 8.74 (d, 2 H), 8.68 (s, 0.3 H), 8.58 (bs, 2
H), 12S4: 4.19-4.10 (m, 3 H), 3.66-3.58 (m, 3 H), 3.53-3.38 (m, 6H), 3.34-3.25 (m, 4
H), 3.11-2.90 (m, 9 H), H2O: 2.08 (s, 3 H). 13C NMR (CD3NO2, ppm) pyr: 151.319 (2
C), 147.334 (2 C), 12S4: 45.705 (2 C), 42.072 (2 C), 34.940 (2 C), 34.435 (2 C).
A4-3. Attempted Preparation of cis-[Ru(12S4)(bpe)Cl]PF6
A mass of [Ru(12S4)(dmso)Cl]Cl (75.0 mg, 0.153 mmol) was added to 16 mL
of a MeOH/H2O mixture (1:1) and the solution was stirred until all of the complex
dissolved. Once everything was in solution a mass of bpe (28.2 mg, 0.153 mmol) was
added to it. The reaction was refluxed under N2 for 19 hours. The reaction was tan in
color. A mass of NH4PF6 (49.9 mg, 0.306 mmol) was added to the reaction, and a
creamy yellow solid formed. The solution was rotary evaporated to saturation and then
chilled in an ice bath. The solid was filtered and washed with a small amount of
ethanol and then ether. During filtration a yellow product was collected on the filter.
After less than 1 mL of MeOH was added, some of the filtered product washed through
and some remained as a tan product. The supernatant was rotary evaporated and
filtered. This produced a yellow solid. Some sample still remained in the supernatant,
and this was set to air evaporate. The final yields were 45 mg (47.9%) of yellow
51
filtered product, 48 mg (51.2%) of tan product, and 36.8 mg (39.2%) of evaporated
supernatant.
The results for the tan colored product were: IR (KBr, cm-1) 3035.47, 2994.50,
2926.22, 2857.94, 1615.21, 1499.13, 1424.02, 1273.80, 1229.41, 1215.76, 1065.54,
840.21 (PF6-), 560.25 (PF6-).
The results for the yellow colored product were: IR (KBr, cm-1) 3019.50,
2936.91, 2872.28, 1615.56, 1554.52, 1497.07, 1421.66, 1267.27, 1220.59, 1066.19,
836.39 (PF6-), 559.91 (PF6-).
B. 9S3 (1,4,7-trithiacyclononane) Chemistry
1. Corner Formation
B1-1. Preparation of fac-[Ru(9S3)(dmso)Cl2]
The synthesis for [Ru(9S3)(dmso)Cl2] was first reported by literature.26
A mixture of [Ru(dmso)4Cl2] (291 mg, 0.600 mmol) and 9S3 (108 mg, 0.600
mmol) was added to a 50 mL flask filled with 25 mL of CHCl3. The solution was
stirred for 2 hours while at reflux. After the stirred reflux for 2 hours, the orange
solution had a yellow precipitate. The precipitate was washed with 3 x 5 mL of CHCl3.
The final yield was 251 mg (98.0%) of fac-[Ru(9S3)(dmso)Cl2].
_______________________
William, Sheldrick S.; Landgrafe, Claudia. “Structure and Reactions of the Thioether
Half-sandwich Ruthenium(II) Complexes [Ru(MeCN)3([9]aneS3)][CF3SO3]2 and
[Ru(MeCN)2(PPh3)([9]aneS3)]pCF3SO3]2 ([9]aneS3 = 1,4,7 – trithiacyclononane).” J.
Chem. Soc. Dalton Trans. 1994, 1885-1886.
26
52
2. Dechlorination of [Ru(9S3)(dmso)Cl2]
B2-1. Thallium hexafluorophosphate dechlorination of fac-[Ru(9S3)(dmso)Cl2]
A mixture of [Ru(9S3)(dmso)Cl2] (475.0 mg, 1.104 mmol), TlPF6 (770.9 mg,
2.207 mmol), and dmso (156.8 μL, 2.207 mmol) were added to 30 mL of dried acetone
in a 50 mL flask. The reaction was brought to reflux, and the reaction changed from a
yellow-orange to a yellow solution. TlCl began to form as a white solid almost
immediately, and the reaction was refluxed for a total of 5 hours. The isolation of the
product and the exclusion of TlCl proved challenging due to the fact that the final
product was a yellow oil. This oiling of the complex could have been avoided if a
different counter anion was used. The reaction was filtered and washed with 3 x 5 mL
of dried acetone. The supernatant was rotary evaporated to dryness and then dissolved
in nitromethane. The TlCl did have some solubility in CH3NO2, and this presented an
isolation problem. The solution was rotary evaporated again to dryness and this time
dissolved in MeOH. Methanol was successful because it dissolved the ruthenium
complex and not TlCl. TlCl was removed through filtration. The yield of TlCl was 543
mg (102%) of a white solid. The supernatant was rotary evaporated again and then
cooled. Upon the slow addition of 5 mL of ether, the complex precipitated. This
yielded 339 mg (70.2%) of yellow [Ru(9S3)(dmso)3](PF6)2 crystals. The ruthenium
sample that was examined via NMR showed a white solid that precipitated from
solution after two days. Additional TlCl was removed through rotary evaporation along
with the use of water and MeNO2 to dissolve the ruthenium complex, but not the TlCl.
The final [Ru(9S3)(dmso)3](PF6)2 complex is an oil. IR (KBr, cm-1) 3031.33, 3006.27,
53
2934.68, 1653.24, 1409.84, 1320.35, 1302.45, 1170.01, 1080.53 (dmso), 1012.52,
908.71 (dmso), 844.28 (PF6-), 726.16, 679.63, 557.93 (PF6-), 489.92, 432.65. 1H NMR
(CD3NO2, ppm) 9S3 and dmso: 3.39 (s, 4 H), 3.35 (s, 2 H) 3.29 (s, 4 H), 3.24 (s, 1 H),
3.08 (d, 2 H), 3.06 (d, 2 H), 3.03 (d, 1 H), 2.98 (d, 1 H), 2.96 (s, 2 H), 2.94 (d, 1 H),
2.83 (d, 1 H), 2.81 (d, 1 H), 2.80 (s, 2 H), 2.78 (d, 1 H), 2.59 (s, 1 H). 13C NMR
(CD3NO2, ppm) dmso: 47.10, 46.61, 9S3: 38.87, 34.43, 34.03.
B2-2. Silver triflate dechlorination of fac-[Ru(9S3)(dmso)Cl2
This experiment is a modification of a literature dechlorination procedure.25
A mass of [Ru(9S3)(dmso)Cl2] (315.6 mg, 0.7332 mmol) was added to a
25 mL flask. To this was added 10 mL of MeOH, dmso (0.9374 mL, 13.20
mmol), and AgCF3SO3 (402.76 mg, 1.5680 mmol). The reaction was light
protected with Al foil, and then heated at reflux for 4 hours. The pale white solid
Ag was filtered, yielding 195.0 mg (92.79%) of white solid. The supernatant
was rotary evaporated to an oil. The oil was redissolved in 3 mL of dried
acetone, and to this was slowly added 2 mL of ether. The mixture was then
shaken for 5 minutes using an automatic shaker. The suspension was
refrigerated overnight, and an orange solid was isolated by filtration. This
yielded 125.4 mg (21.01%) of fac-[Ru(9S3)(dmso)3](CF3SO3)2 as a yellow oil.
1
H NMR (D2O, ppm) δ: 3.39 (s, 0.5 H, minor 9S3), 3.31 (s, 0.5 H, minor 9S3), 3.22
(s, 5.4 H, dmso-O), 2.69-3.19 (m, 12 H, 9S3), 2.62 (s, 12 H, dmso-S), 2.45-2.59 (m,
2.5 H). 13C NMR (D2O, ppm) δ: 119.73 (q, CF3SO3, 2 C), 42.68 (2 C, dmso-O), 38.83
54
(4 C, dmso-S), 35.04 (2 C, 9S3), 32.70 (2 C, 9S3), 29.83 (2 C, 9S3). 19F NMR (D2O,
ppm) δ: -78.607 (CF3SO3).
B2-3. Silver hexafluorophosphate dechlorination of fac-[Ru(9S3)(dmso)Cl2]
This experiment is a modification of a literature dechlorination procedure.25
A mass of [Ru(9S3)(dmso)Cl2] (150 mg, 0.348 mmol) was added to 5 mL of
MeOH in a 25 mL flask that was covered with Al to shield it from light. A mass of
AgPF6 (203 mg, 0.801 mmol) and dmso (86.6 μL, 1.22 mmol) was added. The solution
was refluxed for 3 hours. A yellow complex precipitated at the top of the flask while
purple (photodecomposed) AgCl precipitated. Some AgCl was along the top but most
of the solid was at the bottom. The AgCl was filtered and washed with 3 x 5 mL of
MeOH. It was difficult to separate completely all of the yellow Ru(II) product from the
AgCl. The final yield of AgCl was 124 mg (124%) of purple solid. The rest of the
yellow solution that remained in the flask was concentrated to 3 mL through the use of
the rotary evaporator. The Ru complex was precipitated out of solution through a drop
wise addition of 10 mL of ether. The oily looking product was left to refrigerate over
the weekend. The solidified product was filtered and washed with 3 x 10 mL of ether.
The final yield was 82 mg (29%) of fac-[Ru(9S3)(dmso)3](PF6)2.
3. Binuclear Ru(9S3) Complexes
B3-1. Attempted Preparation of [{Ru(9S3)}2-μ-tpp]( CF3SO3)4
Because the starting [Ru(9S3)(dmso)3](CF3SO3)2 complex was an oil
originally this reaction was run at a three to one stoichiometry instead of two to one.
55
A mass of [Ru(9S3)(dmso)3](CF3SO3)2 (348.0 mg, 0.4275 mmol) was added to
20 mL of a MeOH/H2O mixture (1:1). The solution was stirred until the entire complex
dissolved. A mass of tpp (55.36 mg, 0.1425 mmol) was added to the solution. The
reaction was refluxed for 25 minutes, stirred overnight, and refluxed an additional hour
the following day. The tpp ligand was not soluble in MeOH/H2O solvent at the
beginning, but it dissolved as it reacted with the Ru complex. At the beginning of the
reflux, the color of the reaction changed from yellow to orange. After refluxing for 10
minutes the color of the solution changed to red and after an additional 5 minutes, the
reflux produced a dark red, wine-like, solution. This color did not change after
subsequent refluxing. There was excess tpp ligand present at the end of the reflux, and
this may be due to insufficient ruthenium complex being present at the beginning of the
reaction. The excess tpp ligand was removed as a white solid from the solution through
filtration. The supernatant was rotary evaporated to dryness. It was discerned that the
product complex is an oil. Tests were performed to probe solubility and to purify the
solid complex. Finally, the Ru complex was dissolved in 20 mL of acetonitrile and to
this was slowly added 15 mL of ether, dropwise. This solution was left overnight and
red crystals were obtained through filtration. These red crystals were analyzed. IR
(KBr, cm-1) 3012.49, 2995.15, 2925.79, 2318.93, 2284.25, 1628.84, 1580.29, 1566.42,
1417.30, 1389.56, 1275.12 (CF3SO3-), 1247.38 (CF3SO3-), 1226.57 (CF3SO3-),
1157.22, 1094.80, 1025.44, 914.47, 831.24, 758.42, 637.05, 578.09. 19F NMR
(CD3NO2, ppm) δ: -79.207 (d, CF3SO3-). Because only 2 mg of red crystals were
collected it was difficult to obtain a good proton and carbon NMR spectrum.
56
B3-2. Preparation of [{Ru(9S3)CH3CN}2-μ-tpp](PF6)2
This experiment was altered due to the complex [{Ru(9S3)}2-μ-tpp]( CF3SO3)4
oiling at room temperature. If the counter anion was changed from CF3SO3- to PF6-, it
was hypothesized that the complex might crystallize at room temperature.
A mixture of [{Ru(9S3)}2-μ-tpp](CF3SO3)4 (12.5 mg, 0.00992 mmol) and
N(C4H9)4PF6 (74.08 mg, 0.1984 mmol) was added to 15 mL of dried acetone. The
contents were mixed until all reactants dissolved. The reaction was rotary evaporated to
dryness, and the contents were redissolved in 3 drops of acetonitrile. To this was added
dropwise 10 mL of ether. The product precipitated from the ether solution as a dark red
solid that was an oil at room conditions. The clear ether layer was separated from the
solid product through decantation. The clear solution was allowed to dry through
evaporation and yielded 56.9 mg (76.0%) of [N(C4H9)4]CF3SO3 as a white solid. The
dark red solid product from the reaction was dissolved in a variety of solvents in
different crystallization tubes. These were placed in an ether diffusion chamber. Red
crystals were obtained from the acetonitrile dissolved crystallization tube. These
crystals were sent to Clemson University to be analyzed through X-Ray
Crystallography.
4. Self-Assembly
B4-1. Preparation of a cube: [Ru(9S3)(dmso)Cl2] + bipy
This experiment is a modification of a literature self-assembly procedure.10
The first attempt at preparing a molecular cube involved a mixture of
[Ru(9S3)(dmso)Cl2] (16.1 mg, 0.0375 mmol) and bipy (9.0 mg, 0.056 mmol) being
57
placed in an NMR tube in an 8 to 12 stoichiometric ratio. (The reason for this ratio is
because there are 8 corners in a cube and 12 bridging corner sides). The amount of
[Ru(9S3)(dmso)Cl2] and bipy used in this experiment required 3.5 mL of CD3NO2 to
dissolve the reactants. After monitoring the reaction via 1H NMR spectra for 4 weeks,
there was no apparent change in the NMR data. There was only a decrease in peak
heights. The decrease was due to the formation of a red solid that precipitated from
solution. It was hypothesized that the red solid could be the cube. The red solid may
have precipitated because the solution was saturated. The red solid was isolated,
allowed to dry, dissolved in CD3NO2, and then analyzed by NMR. 1H NMR (CD3NO2,
ppm) δ: bipy: 8.698 (dd, 4.06 H), 7.709 (dd, 4.0 H); 3.252 (s, 0.85 H), 3.061-2.577 (m,
1.53 H, 9S3), 2.5327 (s, 9.26 H)
Another attempt at the experiment was made at a smaller scale, this time the
NMR tube sample would not be touched.
In the second experiment a mixture of [Ru(9S3)(dmso)Cl2] (3.67 mg, 0.00833
mmol) and bipy (2.0 mg, 0.013 mmol) was dissolved in 1 mL of CD3NO2 and placed in
an NMR tube. The results we obtained were the same as in the first attempt. There was
no chemical shift or distortion in the 1H NMR spectra, as reported by Thomas.10
Towards the end of the third week of monitoring this experiment, 1H NMR spectrum
still showed the doublet of doublets characteristic of free bipy. 1H NMR (CD3NO2,
ppm) δ: dmso: 7.725 (d, free bipy), 8.73 (d, free bipy).
B4-2. Attempted Preparation of cube: [{Ru(9S3)}8(μ-pyr)12](CF3SO3)16
58
A mixture of [Ru(9S3)(dmso)3](CF3SO3)2 (120 mg, 0.147 mmol) and pyr (17.7
mg, 0.221 mmol) was added to a 25 mL flask. To this was added 14 mL of a
water/methanol mixture (1:1). The reaction was flushed with nitrogen for 10 minutes,
and then the reaction was refluxed for 48 hours. The final product was an orange-red
solution. The solution was rotary evaporated to dryness, and it was observed that the
product was an oil. After allowing the product to dry through evaporation, it was
dissolved in 1 mL of D2O. The first NMR spectrum was complex with signals from
different species. After the NMR analysis, the contents of the NMR tube were placed
in a 25 mL flask and rotary evaporated to dryness. The contents were redissolved in 3
mL of acetone. To this was added dropwise 5 mL of ether. An orange oil formed from
solution. Everything but the oil was decanted and collected. The oil was allowed to dry
through evaporation. The oil was dissolved in 1 mL of D2O. By weighing the flask
with and without the oil in it, it was determined that the yield was 36.0 mg (34.9%) of
oil. No further analysis has been done on the oil at this time.
C. 16S4 (1,5,9,13-tetrathiacyclohexadecane) Chemistry
1. Side Formation and Dechlorination
C1-1. Preparation of trans-[Ru(16S4)(dmso)(H2O)](CF3SO3)2(dmso)
This experiment is a modification of a literature dechlorination procedure.12
A mixture of [Ru(dmso)4Cl2] (200 mg, 0.413 mmol) and 16S4 (122.4 mg,
0.4130 mmol) were added to a 50 mL flask. A volume of 25 mL of absolute ethanol
was added, and the mixture was heated at reflux for 4 hours, forming an orange
solution. To the orange solution was added, a mass of AgCF3SO3 (211.9 mg, 0.8250
59
mmol) and 18 equivalents of dmso (0.528 mL, 7.43 mmol). The mixture was light
protected, using aluminum foil and tape to cover the condenser and reaction flask, and
then refluxed for 2 hours. Heating was stopped and the reaction cooled at room
temperature for 3 days. The purple-red colored AgCl (photodecomposed) was filtered
using a fine frit yielding 107.9 mg (91.29%) of solid. The supernatant from the reaction
was transferred to a 50 mL flask and rotary evaporated to approximately 10 mL of
volume. The solution was refluxed for an additional 2 hours to see if any AgCl would
precipitate. A white solid did form, and it was removed by filtration by a fine frit.
Following filtration the supernatant was refluxed again. This was repeated two more
times using half hour to hour reflux intervals. A mass of approximately 3 mg of AgCl
was collected per reflux. After the third reflux and filtration, the supernatant was rotary
evaporated to a yellow oil. No additional AgCl formed. The oil was dissolved in about
6 mL of dried acetone. A volume of 5 mL of ether was added drop-wise until
saturation. The solution was refrigerated for 2 hours. The solution was then agitated
using a shaker, and yellow crystals of trans-[Ru(16S4)(dmso)(H2O)](CF3SO3)2(dmso)
formed. The supernatant was decanted, and 5 mL of ether was added. Fine, yellow
crystals were isolated using filtration and 2 x 3 mL of ether washing. Yield was 170.9
mg (51.10%) of yellow trans-[Ru(16S4)(dmso)(H2O)](CF3SO3)2(dmso) crystals. After
D2O dissolution of the complex, it was observed that some AgCl was still present in
the final sample. The AgCl was removed by filtration. An extra clean up step using
water is needed for future reactions. C18H38F6O9RuS8 (MW = 870.07 g/mol) calc. Cl
0.00; found Cl trace: <0.25. 1H NMR (D2O, ppm) δ: 4.77 (s, H2O), 3.57 (s, 6.083 H,
60
dmso-S), 3.11 (qd, 8.0 H, 16S4), 2.98 (td, 8.913 H, 16S4), 2.76 (s, 8.217 H, free dmso),
2.53-2.65 (m, 4.097 H, 16S4), 2.06 (qd, 4.002 H, 16S4). 13C NMR (D2O, ppm) δ:
119.79 (q, 2 C, CF3SO3), 45.81 (2 C, dmso-S), 38.86 (2 C, free dmso), 34.04 (8 C,
16S4), 24.03 (8 C, 16S4). 19F NMR (D2O, ppm) δ:
-78.638 (s, CF3SO3-).
2. Self-Assembly
C2-1. Preparation of a Triangle: [{(4,7-phen)( μ-Ru(16S4))}3](CF3SO3)6
A mixture of trans-[Ru(16S4)(dmso)(H2O)](CF3SO3)2(dmso) (70.0 mg, 0.0805
mmol), from C1-1, and 4,7-phen (14.5 mg, 0.0805 mmol) was added to a 50 mL flask.
To this was added a 10 x excess of dmso (57.0 μL, 0.805 mmol). The reactants were
dissolved in 14 mL of a water/methanol (1:1) mixture. The reaction was flushed with
nitrogen for 15 minutes, and then refluxed for 4 days. The reaction was very dilute and
had a pale yellow color. After the 4 days of reflux, the color of the solution was yellow
and slightly golden. Isolation of this product afforded an oil that was difficult to
solidify. The sample was dissolved in CD3COCD3 and examined by NMR. After the
sample was analyzed with NMR it was rotary evaporated to dryness and washed with
chloroform, but all of the complex and any possible free ligand dissolved. This was
rotary evaporated to dryness and then rinsed with ether to remove any free 4,7-phen
ligand. After the complex dried through evaporation, it was redissolved in D2O and reexamined with NMR. This time the 4,7-phen ligand did not have the chemical shifts of
free ligand for 1H NMR. 1H NMR (D2O, ppm) δ: 4.7-phen: 8.1305 (dd, 2.0 H), 7.6838
(dd, 2.0 H), 6.9461 (q, 2.0 H), 6.8533 (s, 2.0 H); 3.3630 (s, 5.2 H, dmso-S), 2.87042.9323 (m, 7.6 H, 16S4), 2.7914 (td, 8.2 H, 16S4), 2.5852 (s, 4.0 H, free dmso),
61
2.3435-2.4351 (m, 3.9 H, 16S4), 1.8498 (qt, 3.8 H, 16S4). 13C NMR (D2O, ppm) δ:
4,7-phen: 149.0078 (2 C), 144.0402 (2 C), 131.1209 (2 C), 129.3951 (2 C), 123.1118
(2 C), 121.9200 (2 C); 119.767 (q, 2 C, CF3SO3), 45.6338 (2 C, dmso-S), 38.7594 (2 C,
free dmso), 33.9444 (6 C, 16S4), 23.9236 (6 C, 16S4).
C2-2. Preparation of a Hexagon: [{(pmd)( μ-Ru(16S4))}6](CF3SO3)6: NMR Scale
Reaction
A mixture of trans-[Ru(16S4)(dmso)(H2O)](CF3SO3)2(dmso) (64.4 mg, 0.0741
mmol) and pmd (5.83 μL, 0.0741 mmol) were added to a 5 mL flask. To this was
added 1 mL of CDCl3. The reaction was refluxed under nitrogen for 30 minutes. It was
observed that about half of CDCl3 solvent evaporated away and the reaction bumped,
forcing reactants into the condenser. The reactants were collected, and everything was
redissolved in 1 mL of D2O. The reaction was refluxed for an additional 2 hours. All of
the CDCl3 had evaporated away after about 15 minutes. The 1H NMR spectrum
showed very faint ligand proton signals, but there were no ligand signals observed in
the 13C NMR. The NMR sample was added back to the 5 mL flask. To this was added
more pmd (5.83 μL, 0.0741 mmol) and the reaction was refluxed for 22 hours. During
the reaction some insoluble brown complex had formed. The final solution color was
brown in color. The sample was examined by NMR. 1H NMR (D2O, ppm) δ: pmd:
9.2050 (s, 0.935 H, minor), 9.0080 (s, 1.402 H, major), 8.9289 (d, 0.912 H, minor),
8.8602 (dd, 1.359 H, minor), 8.6827 (d, 2.848 H, major), 7.6506 (td, 1.113 H, minor),
7.4765 (td, 1.288 H, major); 3.4523 (s, 2.965 H, dmso-S), 2.6368-3.0503 (m, 33.528 H,
16S4), 2.5944 (s, 28.053 H, free dmso), 2.3114-2.5508 (m, 14.472 H, 16S4). 13C NMR
62
(D2O, ppm) δ: pmd: 175.6474 (1 C, minor), 162.4706 (1 C, major), 161.9653 (1 C,
minor), 157.9989 (1 C, major), 157.3696 (1 C, minor), 157.2456 (1 C, major),
123.2644 (1 C, minor), 122.4730 (1 C, major); 119.69 (q, 2 C, CF3SO3); dmso: 45.6910
(2 C, major dmso-S), 44.5946 (2 C minor dmso-S), 38.7689 (2 C, free dmso); 16S4:
34.5070 (2 C, minor), 34.2781 (2 C, minor), 34.0112 (4 C, major), 33.9063 (2 C,
major), 31.8754 (2 C, minor), 23.9808 (2 C, major), 23.1227 (4 C, minor), 22.9320 (4
C, major).
II. Platinum (II) Chemistry
A. Corner Synthesis
A-1. Preparation of [Pt(9S3)Cl2]
A mass of [Pt(NCPh)2Cl2] (500 mg, 1.06 mmol) was placed in a 125 mL
reaction flask filled with 75 mL of acetonitrile. The solution was stirred slowly in order
to mix it well. A mass of 9S3 (191 mg, 1.06 mmol) was added to the solution. The
reaction was capped with a cork and left untouched over the weekend. After three days,
orange crystals were present on the bottom in an almost clear yellow solution. The
supernatant was decanted and left to evaporate. The crystals were filtered and washed
with 3 x 15 mL acetone and 3 x 15 mL ether. The total yield was 444 mg (99.0%) of
orange [Pt(9S3)Cl2] crystals.
B. Platinum Thiacrown Complexes with Substituted Diimine Ligands
B-1. Preparation of [Pt(9S3)(5,6-dm-phen)](PF6)2
A mass of [Pt(9S3)Cl2] (100 mg, 2.24 mmol) and 5,6-dm-phen (46.7 mg, 2.24
mmol) was added to a 125 mL flask filled with 1:1:1 ratio of 20 of mL methanol, 20
63
mL of acetonitrile, and 20 mL of water. The reaction was refluxed for 6 hours. After
the 6 hour reflux, the reaction was cooled slightly and a mass of NH4PF6 (73.0 mg,
2.24 mmol) was added. After a yellow precipitate formed, the reaction was rotary
evaporated to dryness. A volume of 10 mL of CH3NO2 was added to the flask in order
to re-dissolve as much of the Pt complex as possible. Solid NH4Cl precipitated out as a
colorless solid. The NH4Cl was filtered, and the yellow supernatant was placed in a
crystallization tube, capped with Al foil, and placed in an ether diffusion chamber.
Brown beads crystallized in the tube. These were collected and dissolved in 1 mL of
CD3NO2 for NMR analysis. 1H NMR (CD3NO2, ppm) δ: 5,6-dm-phen: 9.42-9.25 (d,
2.0 H), 9.25-9.20 (t, 2.0 H), 8.26-8.15 (q, 2.0 H), 2.936 (s, 6.00 H); 3.51-3.30 (m, 12.0
H, 9S3). 13C NMR and 13C DEPT NMR (CD3NO2, ppm) δ: 5,6-dm-phen: 150.76 (CH), 139.94 (-CH), 135.08 (-C-), 133.82 (-C-), 128.10 (-CH), 15.67 (-CH3); 34.54
(9S3).
B-2. Preparation of [Pt(9S3)(4,7-dm-phen)](PF6)2
A mixture of [Pt(9S3)Cl2] (100 mg, 2.24 mmol) and 4,7-dm-phen (46.7 mg,
2.24 mmol) was added to a 125 mL flask filled with 1:1:1 ratio of 20 mL of methanol,
20 mL of acetonitrile, and 20 mL of water. The reaction was refluxed for 6 hours. After
the 6 hour reflux, the reaction was cooled slightly and a mass of NH4PF6 (73.0 mg,
2.24 mmol) was added. After a yellow precipitate formed, the reaction was rotary
evaporated to dryness. A volume of 10 mL of CH3NO2 was added to the flask in order
to re-dissolve as much of the Pt complex as possible. Solid NH4Cl precipitated and was
filtered from solution as a colorless solid. The yellow supernatant was placed in a
64
crystallization tube, capped with Al foil, and placed in an ether diffusion chamber. A
brown-black, gooed-up substance that held orange crystals was dissolved in 1 mL of
CD3NO2 and examined by NMR. 1H NMR (CD3NO2, ppm) δ: 4,7-dm-phen: 9.19 (d,
2.0 H), 8.50 (s, 2.0 H), 8.01 (d, 2.0 H), 3.06 (s, 6.01 H), 3.71-3.28 (m, 22.26 H). 13C
and 13C DEPT NMR (CD3NO2, ppm) δ: 4,7-dm-phen: 155.01 (-C-), 151.33 (-CH),
147.70 (-C-), 132.89 (-C-), 128.70 (-CH), 126.30 (-CH); 38.34 (9S3), 34.47 (9S3). 195Pt
NMR (CD3NO2, ppt) δ: -3.30495 (broad).
B-3. Preparation of [Pt(9S3)(4,7-dph-phen)](PF6)2
A mixture of [Pt(9S3)Cl2] (100 mg, 2.24 mmol) and 4,7-dph-phen (74.5 mg,
2.24 mmol) was added to a 125 mL flask filled with 1:1:1 ratio of 20 mL of methanol,
20 mL of acetonitrile, and 20 mL of water. The reaction was refluxed for 6 hours. After
the 6 hour reflux, the reaction was cooled slightly and a mass of NH4PF6 (73.0 mg,
2.24 mmol) was added. After an orange precipitate formed, the reaction was rotary
evaporated to dryness. A volume of 10 mL of CH3CN was added to the flask in order
to re-dissolve as much of the Pt complex as possible. Solid NH4Cl precipitated and was
filtered from solution as a colorless solid. The orange supernatant was placed in a
crystallization tube, capped with Al foil, and placed in an ether diffusion chamber. Red
crystals crystallized, were isolated, allowed to dry through evaporation and were
dissolved in 1 mL of CD3NO2 for NMR analysis. 1H NMR (CD3NO2, ppm) δ: 4,7-dphphen: 9.42 (d, 2.0 H), 8.30 (s, 2.0 H), 8.13 (d, 2.0 H), 7.71 (m, 10 H); 3.61-3.24 (m, 12
H). 13C and 13C DEPT NMR (CD3NO2, ppm) δ: 4,7-dph-phen: 155.53 (-C-), 151.538 (-
65
CH), 148.52 (-C-), 136.30 (-C-), 131.93 (-CH), 131.22 (-CH), 130.70 (-CH), 128.38 (C-), 127.99 (-C-), 126.22 (-C-); 34.63 (9S3).
B-4. Preparation of [Pt(9S3)(5-nitro-phen)](PF6)2
A mixture of [Pt(9S3)Cl2] (100 mg, 2.24 mmol) and 5-nitro-phen (45.1 mg,
2.24 mmol) was added to a 125 mL flask filled with 1:1:1 ratio of 20 mL of methanol,
20 mL of acetonitrile, and 20 mL of water. The reaction was refluxed for 6 hours. After
the 6 hour reflux, the reaction was cooled slightly and a mass of NH4PF6 (73.0 mg,
2.24 mmol) was added. After a yellow precipitate formed, the reaction was rotary
evaporated to dryness. A volume of 10 mL of CH3NO2 was added to the flask in order
to re-dissolve as much of the Pt complex as possible. A mass of NH4Cl precipitated
and was filtered from solution as a colorless solid. The yellow supernatant was placed
in a crystallization tube, capped with Al foil, and placed in an ether diffusion chamber.
Black beads crystallized, were isolated, allowed to dry through evaporation, and were
dissolved in 1 mL of CD3NO2 for NMR analysis. 1H NMR (CD3NO2, ppm) δ: 10.138.04 (m, 7.08 H, 5-nitro-phen) 3.55-3.25 (m, 12 H, 9S3). 13C and 13C DEPT NMR
(CD3NO2, ppm) δ: 5-nitro-phen: 154.866 (-CH), 153.455 (-CH), 151.957 (-C-),
149.688 (-C-), 148.668 (-C-), 144.968 (-CH), 139.744 (-CH), 129.819 (-CH), 129.704
(-CH), 129.075 (-CH), 127.426 (-C-), 126.84 (-C-); 38.353 (9S3), 34.635 (9S3).
B-5. Preparation of [Pt(9S3)(bqn)](PF6)2
A mixture of [Pt(9S3)Cl2] (100 mg, 2.24 mmol) and bqn (57.4 mg, 2.24 mmol)
was added to a 125 mL flask filled with 1:1:1 ratio of 20 mL of methanol, 20 mL of
acetonitrile, and 20 mL of water. The reaction was refluxed for 6 hours. After the 6
66
hour reflux, the reaction was cooled slightly and a mass of NH4PF6 (73.0 mg, 2.24
mmol) was added. After a yellow precipitate began to form the reaction was rotary
evaporated to dryness. A volume of 10 mL of CH3NO2 was added to the flask in order
to re-dissolve as much of the Pt complex as possible. A mass of NH4Cl precipitated
and was filtered from solution as a colorless solid. The yellow supernatant was placed
in a crystallization tube, capped with Al foil, and placed in an ether diffusion chamber.
A yellow powder formed along the sides of the crystallization tube. This powder was
isolated, allowed to dry through evaporation, and was dissolved in 1 mL of CD3NO2
for NMR analysis. 1H NMR (CD3NO2, ppm) δ: bqn: 9.68 (q, 2.0 H), 9.37 (d, 2.0 H),
8.86 (d, 2.0 H), 8.65 (d, 2.0 H), 8.46 (d, 2.0 H), 8.34 (td, 2.0 H), 8.13 (td, 2.0 H), 7.88
(bs, 2.0 H); 3.94-3.55 (m, 11.94 H, 9S3), 3.43-2.99 (m, 12.03 H, 9S3). 13C NMR
(CD3NO2, ppm) δ: bqn: 148.125 (-CH), 146.590 (-C-), 142.519 (-C-), 137.303 (-CH),
132.631 (-C-), 131.516 (-C-), 130.553 (-CH), 124.699 (-CH), 122.0575 (-CH); 42.453
(free 9S3 ligand), 38.363 (9S3).
III. Palladium (II) Chemistry
A. Corner Synthesis
A-1. Preparation of [Pd(9S3)Cl2]
A mass of [Pd(NCPh)2Cl2] (500 mg, 1.30 mmol) was placed in a 125 mL flask
filled with 75 mL of acetonitrile. The solution was stirred until the orange
[Pd(NCPh)2Cl2] dissolved completely. If the solid was to settle, it would not react
completely with the 9S3, and the final product would be contaminated with reactant
still being present. A mass of 9S3 (235 mg, 1.300 mmol) was added and the reaction
67
was capped and left untouched over the weekend. After three days black crystals were
visible in an light orange solution. The supernatant was decanted and left to dry while
the black crystals were filtered off and washed with 3 x 15 mL acetone and 3 x 15 mL
ether. The final yield was 449 mg (96.0%) of [Pd(9S3)Cl2].
B. Self-assembly
B-1. Attempted preparation of square [{Pd(9S3)}4(μ-bipy)4](Cl)4
A mass of [Pd(9S3)Cl2] (7.14 mg, 0.200 mmol) and bipy (3.12 mg, 0.200
mmol) was dissolved in 1 mL of CD3NO2 and placed in an NMR tube. The Pd complex
never dissolved. The 1H NMR monitoring showed no change in the bipy spectrum,
which meant that the self-assembly was not going through to completion. 1H NMR
(CD3NO2, ppm) δ: 8.698 (d, 3.94 H, free bipy), 7.705 (d, 4.0 H, free bipy), 3.357 (m,
1.33 H, 9S3).
A second experiment was performed that followed the same set up. A mass of
[Pd(9S3)Cl2] (7.14 mg, 0.200 mmol) and bipy (3.12 mg, 0.200 mmol) was dissolved in
1 mL of CD3CN and placed in an NMR tube. The Pd complex had no solubility in
CD3CN as well, and the only difference between this and the first experiment was that
the bipy appeared to crystallize in the CD3CN NMR tube. 1H NMR (CD3CN, ppm) δ:
8.69 (d, 4.0 H, free bipy), 7.665 (d, 4.0 H, free bipy), 3.374 (m, 0.13 H, 9S3).
IV. Cancer Screening
A. Preparation of cis-[Pd(9S3)Cl2] for cancer screening
A mass of [Pd(9S3)Cl2] (10.0 mg, 0.0280 mmol) was placed in 5 mL of dmso.
This produced a brown solution, 5.59 mM.
68
B. Preparation of fac-[Ru(9S3)(dmso)Cl2] for cancer screening
A mass of [Ru(9S3)(dmso)Cl2] (10.0 mg, 0.0232 mmol) was placed in 2 mL of
dmso. This produced a yellow solution, 11.6 mM.
69
Results & Discussion
I. Thiacrown Addition
The addition of a thiacrown to the starting [Ru(dmso)4Cl2] complex is a crucial
step in the self-assembly procedure. The thiacrown controls the final self-assembled
product. Our group has successively employed these ligands in the past for Ru and Pt
coordination chemistry. These sulfur macrocycles, especially in the case of Ru, form
very strong bonds to the metal through the sulfur donors. The thiacrowns also have
characteristic 1H and 13C NMR spectra which allows the monitoring of the progress of
the self-assembly. 13C NMR spectroscopy is used to determine the simplicity of the
thiacrown region to determine the binding to the Ru complex. 1H NMR spectroscopy is
used to determine the ratio of thiacrown (attached to the Ru complex) to the linker
ligand.
A. 9S3 (1,4,7-trithiacyclononane)
For all three ligands, 9S3, 12S4, and 16S4, the 1H NMR spectrum will be a
complex set of multiplets. The least complex spectrum is observed for 9S3 complexes
whose 1H NMR spectrum is made up of two sets of multiplets. This is what we refer to
in our group as the “butterfly wings.” The best example of this proton splitting was
observed in a 1H NMR spectrum sample of [Pt(9S3)(4,7-DPh-phen)](PF6)2 . The
spectrum is shown below:
70
These “butterfly wings” are caused by two environments of the protons of the
9S3 ligand. For each methylene carbon there is a hydrogen that points inside the
macrocycle (toward the metal center) and a hydrogen that points outside the
macrocycle (away from the metal center). This is illustrated below:
Ru(9S3)2+
Pt(9S3)2+
The 13C NMR spectrum of a Pt(9S3)2+ or Ru(9S3)2+ is much simpler than the
1
H NMR spectrum. However, because Ru has an octahedral geometry and Pt has a
square pyramidal geometry the 13C NMR spectra will differ in the number of carbon
71
peaks for the two complexes. As mentioned earlier, because of the fluxionality of 9S3
when bound to Pt, there will only be one peak for the 9S3 region. Because of the
fluxionality of the thiacrown, it makes all six carbon atoms magnetically equivalent.
This carbon environment is not observed when 9S3 is bound to Ru. The thiacrown
creates stable bonds with the Ru and does not undergo fluxionality. There exist three
different environments for the 9S3 ligand. These three environments are dictated by the
other three ligands bound to the Ru complex. The three environments are shown
below:
The environment represented by a) shows a complex when all three vacant sites
are coordinated by the same ligand, giving the formula of [Ru(9S3)A3]2+. This type of
environment would show only one 13C NMR peak for the 9S3 ligand. The environment
represented by b) shows a complex where there are two different ligands coordinating
the vacant sites, giving the formula of [Ru(9S3)(A2)B]2+. This type of environment
would make the complex have two 13C NMR peaks for 9S3. This is because there is
only one plane of symmetry in the thiacrown. The environment represented by c)
shows a complex where there are three different ligands coordinating the vacant sites,
giving the formula of [Ru(9S3)ABC]2+. This type of environment would make the
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complex have six 13C NMR peaks for 9S3. There are no planes of symmetry, and the
thiacrown would have every single carbon be magnetically unique. In one of the
cleanest samples obtained, that of [Ru(9S3)(S-dmso)3(O-dmso)](CF3SO3)2, it was
observed that there were two magnetically unique environments of dmso present,
which gave three peaks for the 9S3 region. This is possible because dmso can
coordinate to Ru in two different ways, either through the sulfur or oxygen. The 13C
NMR spectrum of [Ru(9S3)(S-dmso)3(O-dmso)](CF3SO3)2 is shown below:
The spectrum shows that there is a single Ru complex with two dmsos that
coordinate to Ru through sulfur and one dmso that coordinates through oxygen.
Because of this, the thiacrown exists in an environment represented above in b), where
the carbons of 9S3 will be split into three peaks. If self-assembly of a cube was to
occur, via loss of all the dmso ligands, 9S3 would exist in an environment that
produces one peak for 13C NMR of the thiacrown. This is one way of using NMR to
monitor self-assembly and the product formed from the reaction.
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B. 12S4 (1,4,7,10-tetrathiacyclododecane)
12S4 is a tetradentate ligand that binds to Ru leaving two cis oriented reactive
sites. As mentioned in the introduction, the 13C NMR spectrum of the complex is
expected to have four peaks for the 12S4 ligand. Regardless of what the two reactive
sites are, the left side of the thiacrown will be distinct from the right side while the top
of the thiacrown will be the same as the bottom. A figure illustrating the different
possibilities is shown:
The complex shown in a) has two different ligands coordinated at the reactive
sites. This would make the 12S4 have four distinct carbon peaks for 13C NMR even
without taking the invertomers into consideration. The complex shown in b) has same
ligands coordinated at the reactive site. However, this complex would still have four
distinct carbon peaks for 13C NMR because the invertomers make the ligand
unsymmetrical when the sides are compared. The complex shown in c) is the same as
b) except that the invertomers are both pointing outwards and this makes the two sides
of 12S4 symmetrical. This invertomer would have two distinct carbon peaks for 13C
NMR. Throughout this research, all of the complexes obtained for Ru(12S4)2+ have
74
had the invertomer in b), resulting in a four line 13C NMR spectrum for the 12S4
region.
C. 16S4 (1,5,9,13-tetrathiacyclohexadecane)
There are two key aspects of the coordination behavior of the 16S4 ligand. The
thiacrown 16S4 is considerably bigger than 12S4 and therefore it is not able to
coordinate to Ru the same way 12S4 does. That is, 16S4 can form either cis or trans Ru
complexes. Alessio reported that 16S4 reacts with [Ru(dmso)4Cl2] to form exclusively
cis-[Ru(16S4)Cl2].25 This is the same binding that 12S4 forms when coordinated to the
Ru center. However, once the chlorides are removed from the complex through the use
of 2 equivalents of AgCF3SO3, the complex rearranges to trans-[Ru(16S4)(Sdmso)(H2O)](CF3SO3)2(dmso).25 Again, the stability of the thiacrown with regard to
the Ru center is the driving force for this isomerization; the thiacrown is less strained
when it encircles the Ru center. When the two reactive sites of the complex are
chlorides, 16S4 exists in a cis conformation because the chlorides were already in a cis
orientation before the 16S4 was added. These chlorides coordinate very strongly to the
Ru center. Even though 16S4 prefers a trans stereoisomer, it cannot isomerize because
of the coordinated chloride ligands. However, once the chlorides are removed, the
16S4 complex isomerizes into a more stable conformation, and the labile ligands
(dmso, H2O) orient themselves in a trans conformation. This process is shown below:
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The exact mechanism of how 16S4 isomerizes is not yet understood, but a
proposed mechanism is shown below:
The above mechanism is initiated when AgCF3SO3 is used to dechlorinate the
complex. Once one of the chlorides is removed, the thiacrown isomerizes to a stable
orientation. The second chloride is easier to remove because the isomerization of the
16S4 is competing for the chlorides position. The axial sites of the complex will be
coordinated by labile ligands from the solution. AgCl, which is a highly insoluble salt,
will precipitate out of solution.
There are four possible orientations that the 16S4 can orient itself in trans
fashion with regard to the Ru center. This orientation is determined by how the
isopropyl chains that connect the sulfurs in the thiacrown orient their central carbon.
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The carbon can be either up or down in relation to the Ru center. The four possible
orientations are shown below:
Letter a) represents an all up or down orientation, meaning that all of the central
carbons of the isopropyl thiacrown bridges (six-member rings) are pointing in the same
direction. This type of orientation would produce a 13C NMR spectrum with two peaks
for 16S4. Letter b) represents an up, down, up, down orientation, where the central
carbons of the isopropyl thiacrown bridges alternate between being up or down with
respect to their spatial orientation. This type of orientation would produce a 13C NMR
spectrum with four peaks for 16S4. Letter c) represents an up, up, down, down
orientation, where half of the central carbons of the isopropyl thiacrown bridges are
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oriented up and half are oriented down and there is symmetry down the S-Ru-S bond.
This type of orientation would produce a 13C NMR spectrum with six peaks for 16S4.
Letter d) represents an orientation where three of the central carbons of the isopropyl
thiacrown bridges are oriented one way an one of the carbons of the isopropyl
thiacrown bridges is oriented another way. This type of orientation would produce a
13
C NMR spectrum with seven peaks for 16S4.
Throughout this research there has only been one type of 16S4 isomer
observed. This isomer produced two 13C NMR peaks for 16S4, which means that the
16S4 has all of the carbons of the isopropyl thiacrown bridges pointing in one
direction. This is the isomer illustrated in a) above. This isomer is observed in the
crystal structure obtained by Alessio.25 However, Alessio did not perform 13C NMR
spectroscopy on the complex and did not discuss what type of symmetry the isolated
trans-[Ru(16S4)(S-dmso)(H2O)](CF3SO3)2(dmso) structure exhibits. The same
complex was synthesized while performing this research, and the obtained 13C NMR
spectrum is shown below: (13C DEPT NMR was used to distinguish dmso peaks from
16S4 peaks).
78
The solvent used for performing the above NMR analysis was D2O, which
means that the carbon peaks were not referenced to a solvent. The chemical shifts of
16S4 may not have been determined accurately, but the chemical shifts that separate
the 16S4 provide useful information for identifying the 16S4 thiacrown in subsequent
experiments. The two dmso peaks shown originate from the two environments the
dmso are found. The complex described is trans-[Ru(16S4)(Sdmso)(H2O)](CF3SO3)2(dmso). One of the dmso ligands is coordinated to the Ru center
while the other dmso is present in the solution as free dmso. According to Alessio, this
free dmso is stabilized to the complex through a hydrogen bond interaction with the
oxygen from the dmso and hydrogen from the coordinated water of the complex.25
II. Ruthenium Thiacrown Dechlorination
There have been four different attempts to perform dechlorination of ruthenium
thiacrown corners in order to prepare a viable complex with labile ligands that can be
used for self-assembly with connecting ligands. These dechlorination reactions were
categorized by what salt was used to remove the chlorides from the complexes. The
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four methods are: 1) AgNO3 was used to dechlorinate [Ru(12S4)(dmso)Cl]PF6; 2)
AgPF6 was used to dechlorinate fac-[Ru(9S3)(dmso)Cl2]; 3) TlPF6 was used to
dechlorinate [Ru(12S4)(dmso)Cl]PF6; 4) fac-[Ru(9S3)(dmso)Cl2], and AgCF3SO3 was
used to dechlorinate all three thiacrown complexes: [Ru(12S4)(dmso)Cl]PF6, fac[Ru(9S3)(dmso)Cl2], and cis-[Ru(16S4)Cl2]. The dechlorination was monitored by the
formation of white, insoluble AgCl or TlCl that was filtered from the solution. The use
of Ag and Tl presented problems unique to the metal.
A. Silver Dechlorination
AgNO3, AgCF3SO3, and AgPF6 are salts that are moderately sensitive to light.
AgCl, however, is strongly sensitive to light, and brief periods of exposure reduce Ag+
to elemental silver. Unexpected photodecomposition can create unwanted purification
problems in the reaction, which could affect the ruthenium complex present in the
solution. Because the ruthenium complex is one that has been dechlorinated, any
mistakes that occur during this step will greatly influence the self-assembly process.
White AgCl was isolated from the majority of the reactions performed using silver
salts. However, some of the experiments described in the experimental section
produced AgCl that was grey or purple in appearance. This was particularly noticeable
as the AgCl was being filtered from the solution. Filtration was performed in the
laboratory, which contains abundant light. Regardless of the initial color of the AgCl at
the beginning of the filtration, it would be at times purple or dark grey in color by the
end of the filtration. AgCl was also difficult to isolate because it required a fine frit to
adequately filter out the AgCl. However, a fine frit also slowed down the filtration and
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allowed the AgCl to be exposed to light for a longer period of time. The reactions
could have been performed better in a darker laboratory.
The use of Ag salts to dechlorinate the Ru complexes is based upon the
principle that Cl- is a small anion and in order for it to precipitate from a solution it will
have to interact ionically with a small cation, like Ag+. Another factor that drives this
reaction are the big counter anions of Ag+ that interact favorably with the big
ruthenium thiacrown complex.
The first Ag salt that was used to dechlorinate Ru complexes was AgNO3.
According to the yield of AgCl obtained, the AgNO3 dechlorination was effective.
However, subsequent reactions with connecting ligands, particularly that of bipy,
resulted in the formation of bridged complexes. Alessio’s used the same salt to
dechlorinate [Ru(12S4)(dmso)Cl]Cl and observed that 2 equivalents of AgNO3 were
able to dechlorinate the starting complex yielding [Ru(12S4)(S-dmso)(ONO2)](NO3).19
However, when they attempted to self-assemble a square using pyrazine, it was found
that the nitrates bound to the Ru were not easily displaced. The oxygen of the nitrate
that was coordinated to Ru center was so strong that the reaction produced a product of
[{Ru(12S4)(ONO2)}2(μ-pyr)](NO3)2.25 The nitrates, while being able to remove the
strongly coordinated chlorides, presented the complex with the same problem. That is,
the nitrates prevented linker ligands from binding to the Ru center, therefore stopping
self-assembly from occurring.
The dechlorination with AgNO3 was performed so that immediately after the
reaction, AgCl was removed from the solution. The reaction mixture was combined
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with the linker ligand, and the self-assembly reaction was executed. A different
approach was attempted by isolating the dechlorinated complex using a metathesis
reaction to isolate the complex as a PF6- salt. This isolated complex
[Ru(12S4)(dmso)(ONO2)](PF6)2 could then be easily weighed, and self-assembly
reactions could be easily performed because it would require less handling of the silver
salts. It was found that the isolated complex was not very stable once placed back into
solution and ran in a self-assembly reaction because it would decompose in the reaction
flask once at room conditions. The solution would turn brown and the examined
products were not fully self-assembled. The isolated complex would also turn brown if
it was placed in nitromethane and heated. It was determined that isolating the complex
was not favorable because of its low stability. It was also determined that the use of
AgNO3 to dechlorinate afforded a complex that could not be used to self-assemble a
square because of the strongly binding NO3- ligand in the nitromethane solution used
during self-assembly.
Another experiment was performed to determine the effectiveness of AgPF6 in
dechlorinating fac-[Ru(9S3)(dmso)Cl2]. The mass of the Ag salt that precipitated from
the reaction was larger than the theoretical value. Ultimately, the use of AgPF6 as the
means to dechlorinate the Ru complexes was abandoned in favor of AgCF3SO3.
The use of AgCF3SO3 to dechlorinate cis-[Ru(16S4)Cl2] was first reported by
Alessio.25 Throughout this research, AgCF3SO3 was shown to consistently dechlorinate
all three ruthenium thiacrown complexes. The dechlorinated complexes were analyzed
by 1H, 13C, 13C DEPT, and 19F NMR spectroscopy, along with elemental analyses. The
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elemental analyses were obtained for the dechlorination of [Ru(12S4)(dmso)Cl]PF6
and cis-[Ru(16S4)Cl2] and showed only trace amount, less than 0.25%, of Cl present.
This was determined later to be caused by not all of the AgCl being removed from the
complex. That is, after the dechlorination reaction most of the AgCl precipitated out of
solution and was filtered. However, whenever the ruthenium complex was dissolved in
water and allowed to remain in the solution for a given amount of time, there would be
small amounts (around 3 mg) of white solid that precipitated. It was found that if the
complex was repeatedly filtered and allowed to remain in solution for a given amount
of time, then all of the AgCl would eventually precipitate from solution.
One of the benefits of using AgCF3SO3 is that the CF3SO3- counter anion
present on the complex has indicative 13C and 19F NMR. The 13C NMR spectrum of
CF3SO3- has a quartet centered at 119.732 ppm, and the 19F NMR spectrum of CF3SO3has a singlet centered at -78.638 ppm.
There are two issues that were encountered when working with AgCF3SO3.
One is that AgCF3SO3, like the rest of the Ag salts, is able to stain the skin a dark
color. The color fades away after two weeks. The staining is caused by the Ag metal
photodecomposing, which can burn skin tissue. Large amounts of Ag can cause great
discomfort. The other issue faced with using AgCF3SO3 to dechlorinate was that the
CF3SO3- anion would charge balance the Ru complex. Also, it made the overall
complex oily at room conditions. This made the crystallization of a solid complex
difficult. It could not be accurately weighed and used stoichiometrically in selfassembly reactions. This challenge was addressed by dissolving the complex in acetone
83
and adding ether until saturation and then agitating the complex with a shaker. The
exact conditions for this process varied with the thiacrown. Solids were obtained for
triflate salts of Ru complexes with 12S4 and 16S4, but not for 9S3. Another factor that
contributes to the oiling arises from the dmso that is present as a liquid in the complex
from the reaction. Dmso has very low volatility, and it will dissolve the complex.
Because of its low volatility, dmso prevents crystallization of the complex as a solid.
However, the benefits of using AgCF3SO3 to dechlorinate exceed these issues
because it was shown that AgCF3SO3 fully dechlorinates. The labile ligands on the
complex can then be easily displaced by the linker ligands and self-assembly can occur.
B. Thallium Dechlorination
TlPF6 was used in the attempt to dechlorinate [Ru(12S4)(dmso)Cl]PF6 and fac[Ru(9S3)(dmso)Cl2]. The premise for using this thallium salt is that Tl+ is a small
cation and would readily react with Cl- forming an insoluble salt that can be filtered.
One of the biggest concerns with using thallium salts to dechlorinate is that they are
highly toxic. Some of the glassware used for the reactions involving this salt were
designated to be only used for thallium chemistry, especially the frits used to filter
TlCl. The dechlorination did not work as planned as was evident in two ways. There
was excess TlCl being collected, and a white solid would form when the dechlorinated
complex was dissolved in a solvent like nitromethane. If this white solid was TlCl, then
there was too much being collected and the amount that precipitated never reached a
maximum. The other observation that proved that TlPF6 was unable to dechlorinate
[Ru(12S4)(dmso)Cl]PF6 was that once the dechlorinated complex was reacted with
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pyrazine, it was observed that a bridged complex that contained chlorides was isolated
as a crystal structure, that of [{Ru(12S4)Cl}2(μ-pyr)](PF6)2. Because of this
observation, the constant formation of a white solid and the high toxicity of thallium,
the use of TlPF6 was discontinued.
III. Binuclear Complexes
A. 9S3 (1,4,7-Trithiacyclononane)
1. Tetra-(2-pyridyl) pyrazine (tpp)
This experiment was designed to test the ability of AgCF3SO3 to dechlorinate
fac-[Ru(9S3)(dmso)Cl2]. The ligand tpp is potentially a hexadentate ligand with three
nitrogens for coordination on each side of the ligand. Our hypothesis was that if fac[Ru(9S3)(dmso)Cl2] was dechlorinated, the resulting fac-[Ru(9S3)(dmso)3](CF3SO3)2
could be refluxed at a 2:1 stoichiometry with the tpp ligand. The tpp ligand would
coordinate hexadentate to the three reactive sites of the two Ru(9S3)2+ corners. The
complex oiled at room temperature, and therefore clean NMR spectra were not
obtained. However, after experimenting with different solvents and crystallization
methods, single crystals were obtained. The crystal structure is shown below:
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The above structure is that of [{Ru(9S3)(CH3CN)}2(μ-tpp)](PF6)2. The crystal
structure represents a complex that is not the desired product. Our theoretical
experiment was designed as follows:
The reason the crystal structure shows the tpp ligand coordinating tetradentate
instead of hexadentate is because of the structural mismatch between the tpp ligand and
the Ru(9S3)2+ corner. The Ru(9S3)2+ corner has the three reactive sites oriented in a
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face-capping geometry while the three reactive nitrogens on the sides of the tpp ligand
are oriented in a meridional geometry. These two geometries are shown below:
Because of this mismatch, the tpp ligand was utilized in a tetradentate fashion
with one pyridyl group on each side not coordinating. The most useful piece of
information that comes from the crystal structure is that there were no chlorides present
in the structure, which meant that AgCF3SO3 was successful in dechlorinating fac[Ru(9S3)(dmso)3](CF3SO3)2. There were two considerations that needed to be
confirmed by the crystal structure. One was the idea that AgCF3SO3 did not
dechlorinate fac-[Ru(9S3)(dmso)3](CF3SO3)2 and that the tpp ligand removed the
chlorides, and that dmso was later displaced by CH3CN. This hypothesis suggests that
the tpp ligand would rather displace two chlorides instead of a more labile dmso and a
chloride. From past research, it can be concluded that the dmso would be displaced
before the chlorides. In order for the tpp ligand to have coordinated as shown in the
crystal structure, the original complex fac-[Ru(9S3)(dmso)3](CF3SO3)2 must have been
dechlorinated by AgCF3SO3. Another piece of evidence to support this idea is that
CH3CN is present as a ligand on the complex. If dechlorination did not occur and the
tpp ligand displaced a dmso and a chloride, there would still be one chloride left on the
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Ru(9S3)2+ corner. The acetonitrile would not be able to displace this chloride at room
temperature. However, if the complex was originally dechlorinated, then the
acetonitrile would be able to easily displace the labile dmso and coordinate to the
Ru(9S3)2+ corner, as is observed in the crystal structure.
This experiment was successful in establishing AgCF3SO3 as a powerful salt for
dechlorinating the ruthenium thiacrown complex when 9S3 was the ligand. The
[Ru(9S3)]2+ was to be used in the self-assembly of a cube. It was proven through
further work that AgCF3SO3 was also able to dechlorinate ruthenium thiacrown
complexes when 12S4 and 16S4 were the thiacrowns.
B. 12S4 (1,4,7,10-Tetrathiacyclododecane)
1. 1,4-Pyrazine (pyr)
This experiment was designed so that pyr would bridge two Ru(12S4)Cl+ sides.
The final product would be [{Ru(12S4)Cl}2(μ-pyr)](PF6)2. However, this product was
observed when the reaction was run 2:1 (Ru complex : pyr) and 1:1. That is, the same
NMR spectra were observed for the two complexes. The same type of spectra were
observed when pyrazine was used in a self-assembly reaction with what was believed
to be a TlPF6 dechlorinated Ru(12S4)2+ complex. However, because the Ru complex
was not dechlorinated (as evidenced by the result of this reaction) the final product was
[{Ru(12S4)Cl}2(μ-pyr)](PF6)2, event though the reaction was ran 1:1. The crystal
structure obtained of the complex from the self-assembly reaction is shown below:
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The interesting thing was that there were two different environments present for
the 12S4 and the pyrazine 1H NMR and 13C NMR spectra. It was hypothesized that
there were two different isomers present that the binuclear complex orients itself in,
that of the cis and trans, as shown below:
This data was further supported by the observation of two different colors of
crystals that formed during the crystallization and the observed crystal structure of
[{Ru(12S4)Cl}2(μ-bipy)](PF6)2 previously synthesized by Weinan Chen, which shows
a trans isomer exclusively.13 The bipy bridged complex is able to exist as this isomer
exclusively because the sigma bond present in bipy allows the Ru sides to orient
themselves in the most stable conformation, which is that of the trans isomer, as shown
below:
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The crystal structure of [{Ru(12S4)Cl}2(μ-bipy)](PF6)2 is shown below:
However, the hypothesis dealing with two different isomers of the pyrazine
bridged complex did not resolve the question of why the same 1H and 13C NMR spectra
were observed for the two different crystals that were isolated. Depending on the exact
crystal sample, sometimes the integrations would vary, but there would never be just a
single isomer present. The 1H and 13C NMR spectra are shown below:
90
91
The answer to the observed spectra was explained by a mechanism proposed by
a recent paper by Alessio.12 This paper appeared in 2009 following our report of this
chemistry. This mechanism is shown below:
The bridged complex represented by 1 would produce the NMR spectra labeled
by the star. Complexes 2 and 3 would account for the peaks labeled by the circles in
the NMR spectra. Originally, when the argument was that there were two isomers, it
was believed that the pyrazine was in a fixed position in between the two Ru sides.
However, through the NMR spectra, it is observed that the ligand can rotate along the
sigma bonds that coordinate the ligand to the Ru corners. This makes the pyrazine
ligand have a singlet for 1H and 13C NMR. However, in structure 2, the pyrazine ligand
is not equivalent and produces two doublets for 1H NMR and two carbon peaks for 13C
NMR. The dynamics of the equilibrium make these doublets broad because the
pyrazine ligand is equilibrating between a mononuclear complex and acting as a bridge
in a binuclear complex. The twelve carbons observed for the 12S4 ligand originate
from the four carbon peaks from complex 1, four peaks from complex 2, and four
peaks from complex 3.
The solvent allows for this equilibrium to occur, which is also driven by the
small pyrazine ligand. The dimer shows instability due to the close proximity of the
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two Ru(12S4)2+ corners. The instability originates from the solvent used while
performing all of the NMR analysis. The solvent was CD3NO2, which usually contains
around 2% of water per volume of CD3NO2. The low concentration of complex per 1
mL of CD3NO2 means that a small amount of H2O is needed for this equilibrium to
occur. In order to prevent this equilibrium from occurring and to fully characterize the
[{Ru(12S4)Cl}2(μ-bipy)](PF6)2 complex, a solvent free of water should be used.
2. 1,2-Bis(4-pyridyl) ethane (bpe)
This experiment was designed so that bpe would bridge two Ru(12S4)Cl+ sides.
However, a stoichiometry mistake occurred when calculating the reactant amounts
needed and the reaction was run 1:1 instead of 2:1 (Ru complex : bpe). The resultant
complex was not fully characterized.
IV. Self-Assembly
A. 9S3 (1,4,7-Trithiacyclononane)
1. Cube Self-Assembly with 4,4’-Bipyridine
This reaction was designed in order to duplicate the results obtained by
Thomas.10 The reaction between eight equivalents of [Ru(9S3)(dmso)Cl2] and twelve
equivalents of 4,4’-bipyridine did not produce a cube. The reaction was performed at
room temperature in an NMR tube exactly as described in Thomas’s paper.10 However,
the 1H NMR data that we obtained did not indicate a self-assembled cube. Furthermore,
his experiment suggests that bipy was able to displace a chloride from one of the
Ru(9S3)2+ corners and then to displace another chloride from another Ru(9S3)2+
corner, thereby bridging two corners and eventually forming a cube. These results
93
contradict our observations in this research which show that chlorides coordinate
strongly to a Ru center and are not easily displaced except through the use of a specific
salt, like AgCF3SO3. The self-assembly of a cube experiment was performed both in
CD3NO2 and CD3CN. By monitoring the bipy chemical shifts over time it was
observed that the self-assembly of a cube did not occur.
2. Cube Self-Assembly with 1,4-Pyrazine
A clean sample of this product could not be isolated, and the NMR sample
prepared was not concentrated enough to obtain a qualitative spectrum. The experiment
was performed using a AgCF3SO3 dechlorinated [Ru(9S3)(dmso)Cl2] complex and
pyrazine. The only limitations were obtaining a clean sample and enough of it to obtain
a qualitative NMR spectrum.
B. 12S4 (1,4,7,10-Tetrathiacyclododecane)
1. Square Self-Assembly with 4,4’-Bipyridine
Several reactions with bipy have been executed in order to form a selfassembled square with bipy connecting Ru(12S4)2+ corners. However, all of the
products indicated a mononuclear complex. It was not certain why this was occurring,
even after further reflux of already analyzed samples. It became clear that the use of
AgNO3 to dechlorinate ruthenium thiacrown complexes resulted in a nitrate
coordinating to the complex. This nitrate could not be displaced by bipy and therefore
the resulting complex was [Ru(12S4)(ONO2)(bipy)](PF6).
94
2. Square Self-Assembly with 1,4-Pyrazine
This reaction was performed using pyrazine and a TlPF6 dechlorinated
[Ru(12S4)(dmso)Cl](PF6) complex. However, because TlPF6 was unable to
dechlorinate the Ru complex this reaction produced a binuclear complex. This complex
was [{Ru(12S4)Cl}2(μ-pyr)](PF6)2. A discussion of this binuclear complex ha already
been discussed in further detail in the Results and Discussion Section labeled “III.
Binuclear Complexes.”
3. 1,2-Bis(4-pyridyl) ethane (bpe)
The result of this reaction is the formation of a mononuclear complex that was
believed to be [Ru(12S4)(H2O)(bpe)](PF6)2. However, because the original Ru
complex was dechlorinated with AgNO3 it is now understood that the complex formed
is that of [Ru(12S4)(ONO2)(bpe)](PF6)2. The complex was fully characterized with 1H
NMR and 13C, 19F, and 31P NMR spectra. The NMR spectra indicate a mononuclear
complex because there was one to one integration of 12S4 and bpe and the bpe ligand
was unsymmetrical. However, it was not possible to determine with NMR
spectroscopy whether or not ONO2- was coordinated to the Ru center. A crystal
structure of this complex could not be obtained. This reaction served as further proof
that the nitrate coordinates to the Ru center through a strong bond and that the second
nitrogen of the bpe ligand was not able to displace the nitrate and then bridge Ru
corners thereby forming a square.
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4. Square Self-Assembly with 1,4-Dicyanobenzene
A clean sample of this product could not be isolated. Also, the complex started
to turn a brown color after a day of being in solution. The brown complex was not
analyzed by NMR.
5. Square Self-Assembly with Fumaronitrile
A clean sample of the product of this reaction could not be isolated. The 1H
NMR spectrum showed multiple proton peaks for the fum ligand, when the spectrum
should produce only one or two peaks. Further clean up of this product is needed.
C. 16S4 (1,5,9,13-tetrathiacyclohexadecane)
1. Triangle Self-Assembly with 4,7-Phenanthroline
This reaction originally produced a product that had 1H and 13C NMR spectra
indicative of free 4,7-phen ligand. However, after purifying the complex and heating it
in CHCl3 for 10 minutes, different NMR spectra of the complex were obtained. The
NMR spectra indicate self-assembly of the expected [{Ru(16S4)}3(μ-4,7phen)3](CF3SO3)6 complex. The proton integrations of the 4,7-phen region and 16S4
peaks are in a one to one stoichiometry. Because the proton signals for 4,7-phen are not
the same as free ligand (shifted upfield) and are symmetrical, it is concluded that selfassembly did occur. However, because a crystal structure was not obtained, the
complex was not definitely characterized. What is important to note is that the change
in the NMR spectra occurred because the solvent was switched to CHCl3, better
dissolving 4,7-phen. There is ambiguity as to whether the complex should be described
as a hexagon or a triangle. It can be considered a hexagon because there are three
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[Ru(16S4)]2+ sides and three 4,7-phen sides. However, if the 4,7-phen is considered as
a geometry changing corner with linear Ru links, then the complex can be described as
a triangle. The NMR spectra, with the peaks labeled, and the structure of the expected
product are shown below:
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2. Hexagon Self-Assembly with Pyrimidine
The 1H,13C, and 13C DEPT NMR spectra indicate the presence of two different
pyrimidine (pmd) environments present in the solution. One of the environments
represents a symmetrical pmd region and the other represents an unsymmetrical region.
The symmetrical chemical shifts do not match free ligand. Therefore it is observed that
some self-assembly has occurred, most likely to the hexagon. Also, in the sample there
is a second complex present that produces the unsymmetrical pmd chemical shift
peaks. However, because the complex was not purified before being analyzed with
NMR the exact contents of the NMR tube cannot yet be fully characterized.
D. Palladium
1. Square Self-Assembly with 4,4’-Bipyridine
This reaction was designed to determine the ability of [Pd(9S3)Cl2] to react
with bipy in order to form a self-assembled square. Our interest in the experiment was
to determine whether bipy could, under room conditions, displace chlorides and
coordinate to the Pd center. It was observed that no reaction occurred because bipy was
not able to displace the strongly bound chlorides.
V. Platinum Thiacrown Complexes with Substituted Diimine Ligands
The general synthesis of these platinum thiacrown complexes with substituted
diimine ligands involves the reaction of cis-[Pt(9S3)Cl2] with the diimine ligand unique
to the reaction. The diimines coordinate to the Pt center by displacing one of the
chlorides. The second chloride is easily removed by the second imine group of the
chelating diimine ligand. This ability of the second imine to coordinate relatively easily
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is due to the stable 5-membered chelate ring that forms between the Pt center and the
diimine ligand. The displaced chlorides act as the counter anions of the complex. They
are later removed by NH4PF6 yielding NH4Cl and the Pt thiacrown diimine complex as
a PF6- salt. The general procedure, as well as the emphasis of the 5-membered chelate
ring, is shown below:
In order to fully characterize the spectrum obtained through NMR, the
complexes were compared with the NMR spectra of the ligands used that was available
on an internet organic database. This database is the Spectral Database for Organic
Compounds and has been used throughout most of this research.27
_________________________________
27
Spectra Database for Organic Compounds SDBS. March 8, 2010.
<http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi>.
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A. 5,6-dimethyl, 1,10-phenanthroline (5,6-dm-phen)
This reaction was monitored by several instrumental techniques, but the most
important were the analyses of 1H, 13C, and 13C DEPT NMR spectra. 13C and 13C
DEPT NMR spectroscopy was used to determine the presence of the 9S3 ligand on the
Pt center along with the diimine ligand. The integration from the 1H NMR spectrum
was used to determine that the two components were present in the correct 1:1 ratio.
13
C and 13C DEPT NMR spectra are shown below with the peaks labeled:
The labels for the above spectrum is shown in the structure below:
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Using the labeling above, the 1H NMR spectrum peaks were integrated and
identified, as shown below:
Using this information it was clear that the complex [Pt(9S3)(5,6-dmphen)](PF6)2 had been formed. FT-IR spectroscopy was used to confirm the presence
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of PF6-. A crystal structure of this complex was obtained by our group in previous
years thanks to the work of Stephen Ledford. The crystal structure is shown below:
B. 4,7-dimethyl, 1,10-phenanthroline (4,7-dm-phen)
This reaction was monitored by several instrumental techniques, but the most
important were the analyses of 1H, 13C, and 13C DEPT NMR spectra. 13C and 13C
DEPT NMR spectroscopy was used to determine the presence of the 9S3 ligand on the
Pt center along with the diimine ligand. The integration from the 1H NMR spectrum
was used to determine that the two components were present in the correct 1:1 ratio.
Peaks could not all be labeled because the literature values were not known for each
individual carbon or hydrogen peak. The 13C and 13C DEPT NMR spectra are shown
below:
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The structure for the spectrum above is shown below:
The 1H NMR spectrum, with the peaks integrated, is shown below:
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It can be seen from the above spectra that the complex [Pt(9S3)(4,7-dmphen)](PF6)2 had formed. FT-IR spectroscopy was used to confirm the presence of PF6. What is strange about the NMR spectra is that there appear to be two different 9S3
environments. In the 1H NMR spectrum it is observed that the second 9S3 environment
exists as a single peak, which would be the case only if 9S3 was a free ligand. The
spectra above were prepared using a crystallized product so it seems unlikely that there
would be free ligand in the product. However, the integration over the entire 9S3 area
indicates that there are two 9S3 signals present in almost the same amount. Also, the
observation of two 9S3 peaks for the 13C and 13C DEPT NMR indicates that there are
two 9S3 environments present. All of the observations point to a second source of 9S3
present in the final sample. There is need for further purification for a cleaner product.
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A single crystal of the complex was not obtained and therefore there was no crystal
structure available to be studied.
C. 4,7-diphenyl, 1,10-phenanthroline (4,7-dph-phen)
This reaction was monitored by several instrumental techniques, but the most
important were the analyses of 1H, 13C, and 13C DEPT NMR spectra. 13C and 13C
DEPT NMR spectroscopy was used to determine the presence of the 9S3 ligand on the
Pt center along with the diimine ligand. The integration from the 1H NMR spectrum
was used to determine that the two components were present in the correct 1:1 ratio.
Literature values were available for each of the individual carbon peaks, but because of
the coordination of the ligand to the Pt, the chemical shifts changed order. Therefore,
the peaks could not be accurately assigned. The 1H NMR chemical shifts of the ligand
were not available. 13C and 13C DEPT NMR spectra are shown below:
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The structure for the spectrum above is shown below:
The 1H NMR spectrum of the above complex, with the peaks integrated, is
shown below:
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Using the NMR information it was clear that the complex [Pt(9S3)(4,7-dphphen)](PF6)2 was formed during the synthesis. FT-IR spectroscopy was used to confirm
the presence of PF6-. Red, single crystals of the complex were obtained, but a crystal
structure could not be determined. This is unfortunate because the crystal structure was
an important piece of information that was lacking from fully characterizing this
complex.
D. 5-nitro, 1,10-phenanthroline (5-NO2-phen)
This reaction was monitored by several instrumental techniques, but the most
important were the analyses of 1H, 13C, and 13C DEPT NMR spectra. 13C and 13C
DEPT NMR spectroscopy was used to determine the presence of the 9S3 ligand on the
Pt center along with the diimine ligand. The integration from the 1H NMR spectrum
was used to determine that the two components were present in the correct 1:1 ratio.
Literature values were available for each of the individual carbon and proton chemical
shifts of the ligand 5-nitro-phenanthroline. 13C and 13C DEPT NMR spectra, with the
chemical shifts labeled, are shown below:
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The structure for the spectrum above is shown below:
The 1H NMR spectrum of the above complex, with the peaks integrated and
identified, is shown below:
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It can be seen from the above spectra that the complex [Pt(9S3)(5-NO2phen)](PF6)2 was synthesized during the reaction. FT-IR spectroscopy was used to
determine the presence of PF6-. However, looking at the weak signal in the 13C NMR
spectrum and twice as many peaks for 5-NO2-phen as expected in the 1H NMR
spectrum it can be concluded that the complex was not successfully isolated, even after
fractional crystallization. There is also the presence of a second 9S3 species present in
the final sample that was obtained. This 9S3 could be free 9S3 because there is a strong
singlet in the 9S3 region of the 1H NMR spectrum. However, the fact that there are
duplicates of some peaks for the 5-NO2-phen indicates that there could be a second,
minor, [Pt(9S3)(5-NO2-phen)]2+ complex present in the final sample. This is further
supported by the fact that the integrations of all the 5-NO2-phen and all the 9S3 peaks
is in a correct ratio, that is 12 hydrogens for 9S3 and 7 hydrogens for 5-NO2-phen.
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E. 2,2’-biquinoline (bqn)
This reaction was monitored by several instrumental techniques, but the most
important were the analyses of 1H, 13C, and 13C DEPT NMR. 13C and 13C DEPT NMR
spectroscopy was used to determine the presence of the 9S3 ligand on the Pt center
along with the diimine ligand. The integration from the 1H NMR spectrum was used to
determine that the two components were present in the correct 1:1 ratio. Literature
values were available for each of the individual carbon and proton chemical shifts of
the ligand 2,2’biquinoline. However, these chemical shifts could not be labeled
because once the ligand coordinated to the Pt center the chemical shifts changed order.
13
C and 13C DEPT NMR spectra are shown below:
The structure for the above spectrum is shown below:
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The 1H NMR spectrum of the above complex is shown below:
It can be seen from the above spectra that the complex [Pt(9S3)(bqn)](PF6)2
was synthesized during the reaction. FT-IR spectroscopy was used to determine the
presence of PF6-. However, the 13C NMR spectrum shows two 9S3 environments and
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carbon peaks from other solvents present in the NMR tube. Also, there are seven
hydrogen peaks in the 1H NMR spectrum instead of the expected six. Furthermore,
there is a broad singlet just upfield from the 2,2’-biquinoline peaks. This broad peak
integrates to 12 H. It is difficult to try to predict what complex is present in the NMR
sample that is causing the above spectra to be observed. An extra 2 hydrogen
equivalent signal in the 2,2’-biquinoline region would indicate that one of the carbons
or nitrogens on the 2,2’-biquinoline got protonated. However, there would have to be
two equivalent carbons or nitrogens protonated because the spectrum still shows
symmetry. It cannot be the nitrogens because the 2,2’-biquinoline is coordinated, as
indicated by the downfield shift of all of the peaks from free 2,2’-biquinoline peaks. It
is also not one of the quaternary carbons because the use of 13C and 13C DEPT shows
that all three are present. Overall, the NMR sample was not pure enough and not
concentrated enough to obtain a clean NMR spectra. This is probably due to the
complex crystallizing as a powder along the walls of the crystallization tube.
VI. Cancer Screening
A. cis-[Pd(9S3)Cl2]
In order to examine the efficiency of cis-[Pd(9S3)Cl2] as an anti-cancer agent,
the compound was examined via cancer screening in comparison to a current
successful cancer treatment for testicular cancer, Cisplatin. The ability of these
compounds to fight cancer is given as percent kills per molarity. A kill rate over 90% at
100 μg/mL is considered an active agent. Cisplatin showed a 21% kill rate at 100
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μg/mL when performed by Dr. Will Setzer at the University of Alabama-Huntsville.
This kill rate will serve as the effective kill rate to compare versus cis-[Pd(9S3)Cl2].
It was observed that cis-[Pd(9S3)Cl2] was not affective at killing testicular
cancer cells. This was because its percent kill rate at 100 μg/mL was much lower than
that of cisplatin.
B. fac-[Ru(9S3)(dmso)Cl2]
It was also observed that fac-[Ru(9S3)(dmso)Cl2] was not affective at killing
testicular cancer cells because its percent kill rate at 100 μg/mL was much lower than
that of cisplatin as well.
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Conclusions
In achieving self-assembly, this research followed a three step approach:
1. Formation of the metal corner by adding the appropriate thiacrown.
2. Removal of all chloride from the metal corner to provide an open site for a
linker.
3. Reaction of the chloride-free metal corner with the appropriate connecting
ligand to form a molecular square, triangle, cube, or hexagon.
It was determined that all three thiacrowns, 9S3, 12S4, and 16S4, could be
coordinated to Ru(II) through stable bonds that were not broken during subsequent
reactions. It was also observed that the geometrical orientation of 16S4 with the
relation to Ru changes from cis to trans when the complex is dechlorinated.
This research also explored various ways to dechlorinate the ruthenium
thiacrown complexes. It was found that AgCF3SO3 was able to dechlorinate all three
ruthenium thiacrown complexes. However, it was also discovered that AgNO3 was able
to dechlorinate the Ru(12S4)2+ complex, but that during this reaction a nitrate ligand
would coordinate to the Ru. This nitrate was observed to coordinate very strongly to
the Ru and could not be displaced by a connecting ligand.
Throughout this research it was also observed that acetonitrile could coordinate
to the Ru center and that it, like NO3-, could not be displaced by a connecting ligand.
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This research was successful in synthesizing and characterizing the following
bridged and self-assembled ruthenium complexes: [{Ru(9S3)(CH3CN)}2(μ-tpp)](PF6)2,
[{Ru(12S4)Cl}2(μ-pyr)](PF6)2, and [{Ru(16S4)}3(μ-4,7-phen)3](CF3SO3)6(dmso)3.
This research also successfully synthesized and characterized the following
platinum thiacrown diimine complexes: [Pt(9S3)(5,6-dm-phen)](PF6)2, [Pt(9S3)(4,7dm-phen)](PF6)2, [Pt(9S3)(4,7-dph-phen)](PF6)2, [Pt(9S3)(5-NO2-phen)](PF6)2, and
[Pt(9S3)(bqn)](PF6)2.
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