The coordination chemistry of eight chelating heterocyclic ligands is described. These ligands all contain heterocyclic ring systems with bridgehead nitrogens, and have received little attention in the literature. The ring systems examined are, specifically, imidazo[1,2-a]pyridine, imidazo[1,5-a]pyridine and triazolo[1,5-a]pyridine. The coordination complexes synthesised are mononuclear ruthenium(II) complexes, of the type [Ru(bpy)2(L)]2+. Complexes have been examined by a combination of 1H and 13C NMR, UV-visible spectroscopy, cyclic voltammetry, and X-ray crystallography, in order to study their metal-ligand interactions. A total of six complexes were analysed by single crystal X-ray diffractometry, and the resulting structures are described herein. In general, the inclusion of these ligands had the effect of raising the HOMO and lowering the LUMO, relative to the [Ru(bpy)3]2+ complex. As a result, the complexes were easier to oxidise, harder to reduce, and absorb visible light at longer wavelengths.

This thesis describes the preparation and characterisation of a number of homochiral coordination and metallosupramolecular assemblies. These species were formed from the reaction of chiral pyridine and quinoline containing ligands and metal ions. The combination of traditional coordination chemistry and supramolecular interactions led to a range of polymeric and network structures being formed. The ligands used in this thesis can be divided into two broad categories: alkaloids and ligands derived from them, and amino acid-based ligands. In the first category three new ligands were synthesized, and a variety of routes towards alkaloid-based homochiral ligands were investigated. The second category focused on three ligand motifs, and resulted in the preparation of 16 ligands. These two categories of ligands were reacted with a range of metal salts to investigate their coordination and supramolecular chemistry. The structure of twenty complexes was determined by single crystal X-ray crystallography. The complexes had a range of structures, with discrete and polymeric species being formed. Hydrogen bonding was an important feature in the supramolecular chemistry of the complexes, playing a different role in different series of complexes. Two chiral coordination polymers and one chiral coordination network were synthesized. All three of these structures possessed directionality to some degree: in the coordination network and one of the polymers the directionality is counterbalanced by the opposite directionality being present in the crystal, while the second coordination polymer is generated by the screw axis present and has a high degree of overall directionality.

This thesis details the synthesis and coordination chemistry of twenty-five nitrogencontaining heterocyclic ligands, nineteen of which were previously unreported compounds. These ligands were designed for use as synthons for the formation of molecular cages, so contain multiple coordination sites capable of bridging multiple metal atoms. The majority of molecular cages in the literature are formed by rigid bridging ligands, whereas the ligands studied in this research incorporate a higher level of flexibility, thereby lessening the degree of control over the self-assembly process and increasing the number of possible structures that can be formed upon reaction of these ligands with meal salts. Three of the new ligands synthesised were two-armed bridging ligands, which were reacted with a wide variety of metal salts to investigate what self-assembly products were formed. The complexes characterised include a M₃L₃ cyclic trimer, a range of coordination polymers of varying dimensionality, a range of dimeric products and a series of M₄L₆ cage-like molecular squares. However, the majority of ligands studied were three-armed, potentially tripodal compounds, which were envisaged as potential components of M₃L₂ or M₆L₄ molecular cages. The products of self-assembly of these ligands with various metals salts were shown to include a variety of discrete tri- and tetranuclear complexes, a range of coordination polymers of varying dimensionality and interpenetration, and a complex M₆L₄ assembly that appears to be a collapsed coordination cage. Unfortunately some of the ligands synthesised were shown to decompose in the presence of various metal salts, a phenomenon already identified in the literature. Analogues of these decomposition products were synthesised deliberately to identify the potential of a known tridentate ligand as a metallosupramolecular synthon. ¹H NMR spectroscopy, mass spectrometry, elemental analysis, thermogravimetric analysis and X-ray crystallography were used to study the compounds synthesised. The crystal structures of five ligands and fifty-one complexes are discussed.

This thesis describes the preparation and characterisation of a number of homochiral coordination and metallosupramolecular assemblies. These species were formed from the reaction of chiral pyridine and quinoline containing ligands and metal ions. The combination of traditional coordination chemistry and supramolecular interactions led to a range of polymeric and network structures being formed. The ligands used in this thesis can be divided into two broad categories: alkaloids and ligands derived from them, and amino acid-based ligands. In the first category three new ligands were synthesized, and a variety of routes towards alkaloid-based homochiral ligands were investigated. The second category focused on three ligand motifs, and resulted in the preparation of 16 ligands. These two categories of ligands were reacted with a range of metal salts to investigate their coordination and supramolecular chemistry. The structure of twenty complexes was determined by single crystal X-ray crystallography. The complexes had a range of structures, with discrete and polymeric species being formed. Hydrogen bonding was an important feature in the supramolecular chemistry of the complexes, playing a different role in different series of complexes. Two chiral coordination polymers and one chiral coordination network were synthesized. All three of these structures possessed directionality to some degree: in the coordination network and one of the polymers the directionality is counterbalanced by the opposite directionality being present in the crystal, while the second coordination polymer is generated by the screw axis present and has a high degree of overall directionality.

This thesis details the synthesis and coordination chemistry of twenty-five nitrogencontaining heterocyclic ligands, nineteen of which were previously unreported compounds. These ligands were designed for use as synthons for the formation of molecular cages, so contain multiple coordination sites capable of bridging multiple metal atoms. The majority of molecular cages in the literature are formed by rigid bridging ligands, whereas the ligands studied in this research incorporate a higher level of flexibility, thereby lessening the degree of control over the self-assembly process and increasing the number of possible structures that can be formed upon reaction of these ligands with meal salts. Three of the new ligands synthesised were two-armed bridging ligands, which were reacted with a wide variety of metal salts to investigate what self-assembly products were formed. The complexes characterised include a M₃L₃ cyclic trimer, a range of coordination polymers of varying dimensionality, a range of dimeric products and a series of M₄L₆ cage-like molecular squares. However, the majority of ligands studied were three-armed, potentially tripodal compounds, which were envisaged as potential components of M₃L₂ or M₆L₄ molecular cages. The products of self-assembly of these ligands with various metals salts were shown to include a variety of discrete tri- and tetranuclear complexes, a range of coordination polymers of varying dimensionality and interpenetration, and a complex M₆L₄ assembly that appears to be a collapsed coordination cage. Unfortunately some of the ligands synthesised were shown to decompose in the presence of various metal salts, a phenomenon already identified in the literature. Analogues of these decomposition products were synthesised deliberately to identify the potential of a known tridentate ligand as a metallosupramolecular synthon. ¹H NMR spectroscopy, mass spectrometry, elemental analysis, thermogravimetric analysis and X-ray crystallography were used to study the compounds synthesised. The crystal structures of five ligands and fifty-one complexes are discussed.

Ces travaux de thèse se partage en deux parties distinctes : d’une part, les travaux concernant l’insertion du cobalt dans la liaison C(O)–N d’amide non-planaire, et les réactions de catalyse qui en découlent, et d’autre part, le développement d’une nouvelle famille de complexes de cobalt, basé sur ligand 5-(4-pyridyl)dipyrrométhène et ses dérivés. Dans la première partie, qui concerne la catalyse au cobalt avec les dérivés d’amides, la réactivité de différents sels et complexes de cobalt avec les amides non-planaires a été étudiés. L’insertion du cobalt se fait en présence de bipyridine en tant que ligand, dans le DMF, avec du manganèse métallique en tant que système réducteur. L’optimisation des réactions de conversion des amides secondaires en esters et les couplages réducteurs entre amides et iodoaryles est ensuite décrite.Dans la seconde partie, concernant la chimie de coordination du cobalt, le développement de complexes cobalt-dipyrrométhène est présenté. Dans un premier temps, l’optimisation de la synthèse des 5-(4pyridyl)dipyrrométhène décrite, suivi de tests de complexation avec différents précurseurs de cobalt. Le ligand ayant deux sites de coordination, la coordination sélective d’un métal de transition sur un des sites dépends principalement de l’encombrement du site "dipyrrométhène”. Si ce site est suffisamment encombré, le cobalt se chélate préférentiellementsur la partie pyridine. Pour forcer la coordination du cobalt dans la partie dirpyrrin, il est nécessaire de bloquer la partie pyridyl. En coordinant un précurseur de ruthénium photosensible sur la pyridine avant le cobalt, il est possbile d’obtenir un complexe bimétallique cobalt-ruthenium, permettant la photoréduction du cobalt, et donc potentiellement le développement d’une catalyse au cobalt sans réducteur métallique. / This thesis is divided in two distinct part: on one side, the works concerning the cobalt insertion into the C(O)–N bond of non-planar amides, and the resulting reactions, and on the other side, the development of a new family of cobalt complexes, based on the 5-(4-pyridyl)dipyrromethene ligand and its derivatives.In the first part, concerning cobalt catalysis with amide derivatives, the reactivity of different cobalt precursors and complexes toward non-planar amides has been studied. The insertion of the cobalt can be realized in presence of bipyridine as ligand, en DMF, with manganese powder as reductant system. The otpimization of the amide-to-ester conversion and the reductive cross-coupling between amides and iodo-aryl is then described.In the second part, concerning the coordination chemistry of cobalt, the development of cobalt-dipyrromethene complexes is presented. Firstly, the optimization of the 5-(4-pyridyl)dipyrromethene synthesis is described,followed by complexation tests with different cobalt precursors. With two coordination sites on the ligand, the selective coordination of a transition metal on one of the sites depends mainly on the dipyrrin hindrance. If this part is hindered enough, cobalt chelate preferentially on the pyridyl part. To force the cobalt coordination on the dipyrrin part, it is necessary to occupied the pyridyl part. By coordinating a photoensitive ruthenium precursor on the pyridine, it is possible to obtain un bimetallic cobalt-ruthenium complex, allowing the cobalt photoreduction, and potentially the development of a cobalt catalysis without metallic reductant.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal