Cheung, Chi Wai. / "December 2010." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

by Fung Chun-wah. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 117-119). / Abstracts in English and Chinese. / Table of Contents --- p.i / Acknowledgments --- p.v / Abbreviations --- p.vi / Abstract --- p.vii / Chapter PART I: --- ACTIVATION OF CARBON-CARBON BONDS OF NITRILES BY RHODIUM PORPHYRIN RADICAL / Chapter CHAPTER 1 --- General Introduction --- p.1 / Chapter 1.1.1 --- Activation of Carbon-Carbon Bond (CCA) by Transitional Metals --- p.1 / Chapter 1.1.1.1 --- Potential Application of C-C Bond Activation --- p.1 / Chapter 1.1.1.1.1 --- Cracking --- p.1 / Chapter 1.1.1.1.2 --- Depolymerization --- p.2 / Chapter 1.1.1.2 --- Thermodynamic and Kinetic Considerations in CCA --- p.3 / Chapter 1.1.1.3 --- C-C Bond Activation in Strained System --- p.3 / Chapter 1.1.1.4 --- C-C Bond Activation facilitated by Aromatization --- p.7 / Chapter 1.1.1.5 --- C-C Bond Activation of Carbonyl Compounds --- p.9 / Chapter 1.1.1.6 --- C-C Bond Activation of the Nitriles --- p.13 / Chapter 1.1.1.7 --- Selective C-C Bond Activation on a Multimetallic Site --- p.16 / Chapter 1.1.1.8 --- Intramolecular sp2 -sp3 C-C Bond Activation in PCP System --- p.17 / Chapter 1.1.1.9 --- CCA in N-Heterocyclic Carbene --- p.18 / Chapter 1.1.1.10 --- CCA in Pt(0) complexes bearing Chelating P´ةN- and P´ةP- Ligands --- p.19 / Chapter 1. 1.1.11 --- CCA of Alkyne via Hydroiminoacylation by Rh(I) Catalyst --- p.20 / Chapter I. 1.1.12 --- CCA in Homoallylic Alcohol by β-Allyl Elimination --- p.21 / Chapter I. 1.1.13 --- C-C Bond Activation by Metathesis of Alkanes --- p.23 / Chapter I.1.2 --- Structural Features of Rhodium Porphyrins --- p.25 / Chapter I.1.3 --- Objective of the Work --- p.27 / Chapter CHAPTER 2 --- Carbon-Carbon Bond Activation (CCA) of Nitriles by Rhodium Porphyrin Radical --- p.28 / Chapter I.2.1 --- Introduction --- p.28 / Chapter I.2.1.1 --- CCA of Nitroxides by Rhodium(II) Porphyrin Radical Rh(por) --- p.28 / Chapter I.2.2 --- CCA of Nitriles by Rh(tmp) Radical --- p.29 / Chapter I.2.2.1 --- Synthesis of Rh(tmp)Me --- p.29 / Chapter I.2.2.2 --- Synthesis of Rh(tmp) Radical --- p.30 / Chapter I.2.2.3 --- Ligand effect on CCA --- p.31 / Chapter I.2.2.3.1 --- Synthesis of Phosphines --- p.31 / Chapter I.2.2.3.2 --- Reactions between Rh(tmp) and Phosphines --- p.32 / Chapter I.2.2.3.3 --- Synthesis of Alkyl Rh(tmp) --- p.35 / Chapter I.2.2.4 --- CCA of Nitriles by Rh(tmp) with PPh3 added --- p.36 / Chapter I.2.2.4.1 --- Synthesis of Nitrile --- p.36 / Chapter I.2.2.4.2 --- Reactions between Rh(tmp) and Nitriles --- p.37 / Chapter I.2.3.4 --- Proposed Mechanism of CCA --- p.44 / Chapter CHAPTER 3 --- Experimental Section --- p.46 / Conclusion --- p.63 / References --- p.64 / Chapter PART II --- ACTIVATION OF CARBON-SILICON BONDS OF NITRILES BY RHODIUM PORPHYRIN RADICAL --- p.71 / Chapter CHAPTER 1 --- General Introduction --- p.71 / Chapter II. 1.1 --- Carbon-Silicon Bond Activation by Transitional Metals --- p.71 / Chapter II. 1.1.1 --- Potential Application of C-Si Bond Activation --- p.72 / Chapter II.l. l.2 --- C(sp3)-Si Bond Activation --- p.73 / Chapter II. 1.1.2.1 --- Intermolecular C(sp3)-Si Bond Activation in Strained System --- p.73 / Chapter II. 1.1.2.2 --- Intermolecular C(sp3)-Si Bond Activation in Unstrained System --- p.76 / Chapter II. 1.1.3 --- C(sp2)-Si Bond Activation --- p.78 / Chapter II. 1.1.3.1 --- Intermolecular C(aryl)-Si Bond Activation --- p.78 / Chapter II. 1.1.3.2 --- Intramolecular C(aryl)-Si Bond Activation --- p.84 / Chapter II. 1.1.3.3 --- C(vinyl)-Si Bond Activation --- p.87 / Chapter II. 1.1.4 --- C(sp)-Si Bond Activation --- p.89 / Chapter II. 1.2 --- Objective of the Work --- p.92 / Chapter CHAPTER 2 --- Carbon-Silicon Bond Activation (CSA) of Nitriles --- p.93 / Chapter II.2.1 --- Introduction --- p.93 / Chapter II.2.2 --- Reactions between Rh(tmp) Radical and Silylnitriles --- p.93 / Chapter II.2.2.1 --- Investigation the CSA of Trimethylsilylcyanide by Rh(tmp) --- p.93 / Chapter II.2.2.1.1 --- Synthesis of Rh(tmp)SiMe3 --- p.93 / Chapter II.2.2.1.2 --- Synthesis of Rh(tmp)CN --- p.94 / Chapter II.2.2.1.3 --- Reactions between Rh(tmp) and Trimethylsilylcyanide --- p.95 / Chapter II.2.2.1.4 --- Ligands effect on CSA of Trimethylsilylcyanide by Rh(tmp) --- p.98 / Chapter II.2.2.1.5 --- Temperature effect on CSA --- p.101 / Chapter II.2.2.2 --- Reactions between Rh(tmp) and other Silylnitriles --- p.102 / Chapter II.2.3 --- Mechanism of CSA of Trimethylsilylcyanide --- p.103 / Chapter II.2.3.1 --- Proposed Mechanism of CSA of Trimethylsilylcyanide by Rh(tmp) --- p.104 / Chapter II.2.4 --- A Comparison of CSA and CCA of Nitriles --- p.105 / Chapter CHAPTER 3 --- Experimental Section --- p.107 / Conclusion --- p.116 / References --- p.117 / List of Spectra --- p.120 / Spectra --- p.121

Radical cyclizations have been proven to be extremely important in organic synthesis. However, their reliance on toxic trialkyltin hydrides has precluded their practical applications in pharmaceutical manufacturing. Many tin hydride substitutes have been suggested but none of them are adequate alternates to the traditional tin reagent. Transition-metal hydrides have been shown to catalyze the hydrogenation and hydroformylation of unsaturated carbon-carbon bonds. Theses reactions begin with a Hydrogen Atom Transfer (HAT) from a metal to an olefin, generating a carbon-centered radical. The cyclization of that radical is an effective route to five- and six-membered rings. The HAT will be fastest if the M–H bond is weak. However, making the reaction catalytic will require that the hydride can be regenerated with H2. HCr(CO)3Cp has proven to be a good catalyst for such cyclizations, but it suffers from air sensitivity. The yield of the cyclization product depends on how the rate of radical cyclization compares with the rates of side reactions (hydrogenation and isomerization), so special substituents on a substrate are best installed to increase the cyclization rate. In attempting to improve the efficiency of radical cyclization I have studied the effect of substituents on the target double bond on the rate of cyclization. A single phenyl substituent has proven to stabilize a radical better than two phenyls. This stabilization leads to faster cyclizations and a higher cyclization yield. I also have found that Co(dmgBF2)L2 (L = THF, H2O, MeOH…) under H2 is an effective hydrogen atom donor. I have monitored by NMR the catalysis by the system of the hydrogenation of stable radicals (trityl radical and TEMPO radical) and found the rate-determining step to be the activation of hydrogen gas by CoII. The reactive form of the complex is five-coordinated cobalt complex Co(dmgBF2)2L. The Co/H2 system can also transfer hydrogen atom to C=C bonds, thus initiate radical cyclizations. The resting state of the cobalt is the CoII metalloradical, so a cycloisomerization is obtained. Such a reaction neither loses nor adds any atom and has 100% atom economy.

by Tam Tin Lok Timothy. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 75-81). / Abstracts in English and Chinese. / Table of Contents --- p.i / Acknowledgments --- p.iv / Abbreviations --- p.vi / Structural Abbreviations for Porphyrin Complexes --- p.vii / Abstract --- p.viii / Chapter Chapter 1 --- GENERAL INTRODUCTION --- p.1 / Chapter 1.1 --- Carbon-Carbon Bonds Activation by Transition Metal Complexes --- p.1 / Chapter 1.1.1 --- Kinetic and Thermodynamic Considerations in CCA --- p.2 / Chapter 1.1.2 --- C-C Bond Activation in Strained System --- p.3 / Chapter 1.1.3 --- C-C Bond Activation Driven by Aromatization --- p.4 / Chapter 1.1.4 --- C-C Bond Activation of Carbonyl Compounds --- p.5 / Chapter 1.1.5 --- Intramolecular sp2-sp3 C-C Bond Activation in PCP system --- p.8 / Chapter 1.1.6 --- C-C Bond Activation in Homoallylic Alcohol by β-Allyl Elimination --- p.10 / Chapter 1.1.7 --- C-C Bond Activation by Metathesis of Alkanes --- p.11 / Chapter 1.1.8 --- C-C Bond Activation by Nucleophilic Attack of Rhodium Porphyrin Anion --- p.14 / Chapter 1.2 --- Objective of the work --- p.14 / Chapter CHAPTER 2 --- CARBON-CARBON BONDS ACTIVATION (CCA) BY RHODIUM PORPHYRIN RADICAL --- p.16 / Chapter 2.1 --- Serendipitous Discovery of CCA --- p.16 / Chapter 2.1.1 --- Proposed Mechanism of CCA --- p.16 / Chapter 2.2 --- CCA of Rhodium Porphyrin Radical witn Nitroxides --- p.17 / Chapter 2.2.1 --- Synthesis of Rhodium Porphyrins --- p.18 / Chapter 2.2.2 --- Synthesis of Rhodium(II) Porphyrin Radical --- p.19 / Chapter 2.2.3 --- "Synthesis of 1,1,3,3-Tetraalkylisoindolin-2-oxyls" --- p.19 / Chapter 2.2.4 --- Reactions between Rhodium(II) Porphyrin Radical and Nitroxides --- p.21 / Chapter 2.2.5 --- Independent Synthesis of Alkyl Rhodium(III) Porphyrins --- p.24 / Chapter 2.3 --- CCA of Rhodium Porphyrin Radical with Other Substrates --- p.26 / Chapter 2.3.1 --- Reactions between Rhodium(II) Porphyrin Radical and Non-enolizable Ketones --- p.26 / Chapter 2.3.2 --- Reactions between Rhodium(II) Porphyrin Radical and Diketones --- p.27 / Chapter 2.4 --- Ligand Effects on Carbon-Carbon Bonds Activation --- p.28 / Chapter 2.4.1 --- Ligand Coordination between Rhodium(II) Porphyrin Radical --- p.29 / Chapter 2.4.2 --- Phosphine Effects on CCA between Rhodium(II) Porphyrin Radical and Nitroxides --- p.31 / Chapter 2.5 --- Summary --- p.32 / Chapter CHAPTER 3 --- PRELIMINARY MECHANISTIC STUDIES OF CARBON- CARBON BONDS ACTIVATION (CCA) --- p.33 / Chapter 3.1 --- Attempted Mechanistic Studies of CCA --- p.33 / Chapter 3.1.1 --- Proposed Mechanism of CCA via SH2 Pathway --- p.33 / Chapter 3.1.2 --- Homolytic Bimolecular Substitution (Sr2) --- p.33 / Chapter 3.1.3 --- Literature Review on Sh2 Reaction --- p.34 / Chapter 3.1.4 --- Prerequisities on SH2 reactions at Carbon Center --- p.36 / Chapter 3.1.5 --- Kinetic Studies of CCA between Rh(tmp) and TEMPO…… --- p.37 / Chapter 3.2 --- Stereochemical Test for CCA --- p.39 / Chapter 3.2.1 --- Objective of the Stereochemical Test --- p.39 / Chapter 3.2.2 --- Synthesis of Alkyl Rhodium(III) Porphyrins --- p.42 / Chapter 3.2.3 --- Alkyl Exchange Reactions with Rh(por)R --- p.42 / Chapter 3.3 --- Summary --- p.43 / Chapter CHAPTER 4 --- EXPERIMENTAL SECTION --- p.45 / CONCLUSION --- p.74 / REFRENCES --- p.75 / LIST OF SPECTRA --- p.82 / SPECTRA --- p.83

Imidazolium trans-[tetrachloro (dimethyl sulfoxide)(imidazole)ruthenate(III)], NAMI-A, is an experimental metastasis inhibitor whose specific mechanism of activation and action remains to be elucidated. In the nucleophilic and reducing physiological environment; it is anticipated that the most relevant and available reductants upon introduction of NAMI-A as a therapeutic agent will be the biologically-relevant free thiols. The kinetics and mechanisms of interaction of NAMI-A with biologically-active thiols cysteamine, glutathione, cysteine and a popular chemoprotectant, 2-mercaptoethane sulfonate (MESNA) have been studied spectrophotometrically under physiologically-relevant conditions. The reactions are characterized by initial reduction of NAMI-A with simultaneous formation of dimeric thiol and subsequent ligand exchange with water to various degrees as evidenced by Electospray Ionization Mass Spectrometry. Stoichiometry of reactions shows that one molecule of NAMI-A reacted with one mole of thiol to form corresponding disulfide cystamine, dimeric MESNA, oxidized glutathione and cystine. Observed rate constants, ko, for the reaction of NAMI-A with cysteamine, MESNA, GSH and cysteine were deduced to be 6.85 + 0.3 x 10-1, 9.4 + 0.5 x 10-2 , 7.42 + 0.4 x 10-3 and 3.63 + 0.3 x 10-2 s-1 respectively. Activation parameters determined from Arrhenius plots are indicative of formation of associative intermediates prior to formation of products. A negative correlation was obtained from the Brønsted plot derived from observed rate constants and the pKa of the different thiols demonstrating significant contribution of thiolate species towards the rate. In conclusion, interactions of NAMI-A with biologically-active thiols are kinetically and thermodynamically favored and should play significant roles in in vivo metabolism of NAMI-A.

This thesis reports the synthesis, characterisation and DNA binding of a number of novel ruthenium(II) complexes. Four mononuclear complexes were synthesised. These complexes were resolved using a large scale extraction procedure employing the chiral TRISPHAT anion. The racemic mononuclear complexes containing halogenated ligands were used in the synthesis of the racemic dinuclear complexes. Resolved mononuclear complexes were also used to stereo-selectively synthesise enantiomers of their respective dinuclear complexes. All metal complexes were characterised using fluorescence spectroscopy. Resolved metal complexes were further characterised using CD spectroscopy to determine their molar rotation coefficients and optical purity. Preliminary DNA binding studies were conducted using the racemic dinuclear complexes and their mononuclear equivalent. Titration experiments with calf thymus-DNA were used to determine the DNA binding constant and binding site size. Samples containing a higher NaCl concentration (100 mM) slightly improved the oligonucleotide spectrum resolution, but not to an extent where a complex binding model could be determined. Attempts to determine DNA binding preferences of the dinuclear complexes with oligonucleotides which contain two-adenine bulge sites using a 96-well a fluorescence plate reader were attempted, but were unsuccessful. Samples containing a higher NaCl concentration (100 mM) slightly improved the oligonucleotide spectrum resolution, but not to an extent where a complex binding model could be determined. Attempts to determine DNA binding preferences of the dinuclear complexes with oligonucleotides which contain two-adenine bulge sites using a 96-well a fluorescence plate reader were attempted, but were unsuccessful. / Doctor of Philosophy (PhD)

This thesis describes the investigation of the coordination and supramolecular chemistry of three different types of pyridine-containing ligand with a selection of Ag(I), Cu(I), Cu(II) and Cd(II) salts. The ligand types are flexible and four-armed, rigid and four-armed and bent with two rigid arms. All the ligands also display the ability to form additional supramolecular interactions. Chapter one introduces supramolecular chemistry and crystal engineering and covers background on several areas of current interest in these fields. Network structures, both coordination polymers and hydrogen-bonded systems, are discussed and topological analysis as a method of describing and comparing network structures is introduced. An outline of the ligand design, choice of transition metals and anions is given. Chapter two provides a review of flexible four-armed pyridine-containing ligands and their use in coordination chemistry. The synthesis and characterisation of three flexible four-armed ligands 1,2,4,5-tetrakis(2-pyridylmethyl-sulfanylmethyl)benzene (2tet), 1,2,4,5-tetrakis(3-pyridylmethyl-sulfanylmethyl)benzene (3tet) and 1,2,4,5-tetrakis(4-pyridylmethyl-sulfanylmethyl)benzene (4tet) are given. The synthesis and characterisation of the Ag(I), Cu(II) and Cd(II) complexes formed with these three ligands are also given. The complex of [Cd(2tet)(NO₃)₄] was structurally characterised by X-ray diffraction and was found to be a discrete species. The complexes {[Ag₂(3tet)](ClO₄)₂}n̲, {[Ag₂(3tet)](PF₆)₂}n̲, {[Ag₂(3tet)](CF₃CO₂)₂}n̲, {[Ag₂(4tet)]-(ClO₄)₂�2MeCN�2CHCl₃}n̲, {[Ag₂(4tet)](PF₆)₂�6MeCN}n̲ and {[Ag₂(4tet)](ClO₄)₂-�3H₂O}n̲ were likewise structurally characterised by X-ray diffraction. All these complexes were three-dimensional coordination polymers. A comparison of the seven structures is given at the end of the chapter. Chapter three reviews rigid four-armed pyridine-containing ligands and their use in coordination chemistry. The preparation of the rigid four-armed ligand 2,3,4,5-tetrakis(4-pyridyl)thiophene (pyth) is given. The synthesis and characterisation of the Ag(I), Cu(I) and Cd(II) complexes formed with this ligand are also given. The complexes [Ag(pyth)](BF₄)�3MeCN�CH₂Cl₂}n̲, [Ag(pyth)](PF₆)�MeCN�CH₂Cl₂}n̲, [Ag(pyth)]-(CF₃SO₃)�2MeCN�CH₂Cl₂}n̲, [Cu(pyth)](PF₆)�MeCN�CH₂Cl₂}n̲ and [(Cu₂I₂)(pyth)]-(BF₄)�1/2CH₂Cl₂�H₂O}n̲ were structurally characterised by X-ray diffraction. The complex with CuI was a two-dimensional coordination polymer, and the other four complexes were three-dimensional coordination polymers. A comparison of the five structures is given at the end of the chapter. Chapter four begins with a review of rigid angular bridging ligands and their use in coordination and supramolecular chemistry. The preparation of the ligand bis(4-pyridyl)amine (bpa) is given. The structural arrangement of bpa in the solid state was determined by X-ray diffraction. Complexes of Ag(I), Cu(I), Cu(II) and Cd(II) formed with this ligand were synthesised and characterised. The complexes {[Ag(bpa)(MeCN)](CF₃SO₃)}n̲, {[Ag(bpa)](PF₆)�MeCN}n̲, {[Ag(bpa)](ClO₄)-�2MeCN}n̲, {[Ag(bpa)](ClO₄)}n̲, {[Ag(bpa)](NO₃)}n̲, [(Cu₂I₂)(bpa)₂]n̲, {[Cu(bpa)₂Cl₂]-�3DMF�3/2H₂O}n̲, {[Cd(bpa)₂(NO₃)(H₂O)](NO₃)}n̲, {[Cd(bpa)₂(SO₄)(H₂O)]�3H₂O}n̲, [Cd(bpaH)₂(SO₄)₂(H₂O)₂]�2MeCN and {[Cd(bpa)(SCN)₂]�1/5iPrOH}n̲ were structurally characterised by X-ray diffraction. All complexes with Ag(I) were one-dimensional coordination polymers, with two of them helical, the other three zigzag. Both complexes with Cu(I) and (II) were two-dimensional coordination polymers. One complex with CdSO₄ was discrete, with the bpa ligands mono-protonated, but all other three other Cd(II) complexes were three-dimensional coordination polymers. Seven of these complexes showed hydrogen-bonding interactions linking them together to form supramolecular structures of higher dimensionalities. A comparison of the twelve structures is given at the end of the chapter. Chapter five is a brief summary of the outcomes of this thesis.

In dieser Arbeit wurden die Molekülstrukturen und die elektronischen Eigenschaften von Vanadium(IV)- und Oxo-Rhenium(V)-Chelaten mit einem kombinierten molekülmechanisch-quantenchemischen Ansatz untersucht, um sterische und elektronische Effekte der Komplexierung mit einem theoretischen Modell zu quantifizieren. Es konnte gezeigt werden, daß auf diese Weise detaillierte Aussagen zu den Bindungsverhältnissen der Metallchelate getroffen werden können. Die Berechnung der Molekülstrukturen gelingt mit exzellenter Übereinstimmung mit den Kristallstrukturen der Komplexe. Die molekülmechanischen Berechnungen erfolgen auf der Grundlage des Extensible Systematic Force Field ESFF und des Consistent Force Field 91 (CFF91). Dabei konnte die hohe Flexibilität und Zuverlässigkeit des regelbasierten ESFF für eine Vielzahl verschiedenster Metallchelate nachgewiesen werden. Aufgrund der mangelhaften Ergebnisse für trigonal-prismatische Komplexgeometrien mit dem ESFF wurden eine Anpassung des CFF91 für derartige Vanadiumkomplexe vorgenommen. Auf Grundlage von theoretischen Ergebnissen wurden die alternativen Strukturen von isoelektronischen Vanadiumkomplexen berechnet und in Übereinstimmung mit experimentellen Daten, theoretischen Modellen der Komplexchemie und empirischen Fakten eine Hypothese für die Ursache der strukturellen Differenzen erarbeitet.<br> Der hier vorgestellte, kombinierte Algorithmus aus kraftfeldbasierter Geometrieoptimierung und single-point-Rechnung an diesen Strukturen ist ein zuverlässiger und relativ schneller Weg Molekülgeometrien von Metallkomplexen zu berechnen. Er kann somit zur Voraussagen von Komplexstrukturen und zur gezielten Modellierung definierter Koordinationsgeometrien verwendet werden. / In this work the molecular structures and the electronic properties of Vanadium(IV)- and Oxo-Rhenium(V)-chelates have been investigated to quantify steric and electronic effects of complexation. It has been shown, that in this way detailed insight can be gained into the bonding conditions of that metal complexes. Molecular mechanic calculations based on the Extensible Systematic Force Field (ESFF) and the Consistent Force Field 91 (CFF91) have been carried out. High flexibility and reliability of the rule based ESFF has been proven for a large variety of different metal chelates. Due to the poor ESFF-results for trigonal-prismatic complex geometries, a fit of the CFF91 for that species was done. Based on the theoretical results the alternative structure of isoelectronical vanadium(IV)- complexes have been calculated and a hypothesis on the reason for the structural differnces have been stated in accordance with experimental results, theoretical models of complex chemistry, and empirical facts. This combined approach of force field based geometry optimization and single point calculation at these structures has been proven to be a reliable and fast way to get molecular structures of metal complexes. It can be used to predict complex structures for modelling destinct coordination geometries.

Thesis (Ph. D.)--University of Chicago, Department of Chemistry, 2002. / Includes bibliographical references. Also available on the Internet.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy