<p>1,1-Dimethyl-3-phenyl-1-germacyclopent-3-ene (32) was synthesized and it was used for the study of the reactivity of diphenylgermylene (GePh₂) toward alkenes using steady state and nanosecond laser flash photolysis technique (nLFP) in hexanes solution.</p> <p>The reactivity of GePh₂ toward several alkenes including 1-hexene, cis-2-hexene, trans- 3-hexene, cyclopentene, cyclohexene, cis-cyclooctene, methylcyclohexene, 2-methyl-2- pentene, 2-methyl-1-pentene and trans-3-methyl-2-pentene has been investigated by nLFP method. In all cases, the equilibrium constant was measured and it was found that there is a direct correlation between the Gibbs free energy of the reaction (∆G_r) and the ionization potential (IP) of the involved alkene. This indicates that alkenes with higher IP, electron poor alkenes, should lead to more stable germiranes and consequently installation of electron withdrawing groups on alkenes should stabilize the resulting germirane. This is the first time such a quantitative predictor is reported.</p> <p>Steady state photolysis methods have been used to investigate same aspects of germirane reactivity. Photolysis of 32 in the presence of acrylonitrile and methanol in one experiment, and 3,3-dimethyl-1-pentene and methanol in another experiment, has provided more evidence for the presence of the corresponding germiranes which were trapped by methanol.</p> <p>Finally, the (1+2) cycloaddition reactions of GeH₂, GeMe₂ and GePh₂ with a selection of alkenes were investigated computationally using different DFT methods and 6-311+G(d,p) as the basis set. The results show that the reaction becomes less exergonic moving from GeH₂to GeMe₂ and then to GePh₂. In addition, plots of calculated ∆G_r against the experimental IP of the involved alkene reproduced the observed experimental correlation from the laser studies. It was also concluded that ωB97XD and mPW1PW91 are the most reliable of the DFT methods that were investigated.</p> / Master of Science (MSc)

Ce travail présente la synthèse de ligands mixtes germylène-sulfoxyde qui ont été utilisés en chimie de coordination avec plusieurs métaux de transitions et finalement appliqués en catalyse de transfert d'hydrogène. Une seconde partie de ce travail est axée sur la synthèse de nouveaux métallylènes stabilisés par un sulfonimidamide qui ont été appliqués en catalyse de polymérisation. Le premier chapitre présente l'état de l'art des germylènes avec leurs synthèses, modes de stabilisations et finalement leur chimie de coordination et leurs applications en catalyse. Les sulfoxydes seront aussi décrits pour leur application en tant que ligands hémilabiles. Le second chapitre décrit la synthèse de ligands germylène-α-sulfoxide avec une diversité structurale (cyclohexyle, tBu, tolyle..) et avec différents degrés d'oxydation du souffre (thioéther, sulfoxyde et sulfone). La chimie de coordination a permis la synthèse de complexes bis-germylène du groupe IV, bidentes du ruthénium ainsi que monodentes du ruthénium. Le troisième chapitre présente l'extension de la méthodologie à la formation de ligands germylène-β-sulfoxide. L'influence du groupement espaçant les deux entités sur la chimie de coordination a été étudiée et montre la formation de complexes bidentates du groupe IV. La coordination du ruthénium a mené à la surprenante synthèse d'un complexe bis-ruthénium caractérisé par diffraction des rayons X. Finalement, la nouvelle architecture a permis d'obtenir des complexes de nickel (0) dont une structure avec des ligands carbonyles permettant une comparaison TEP. Le chapitre quatre présente la synthèse de nouveaux ligands, analogues des amidinates, pour la stabilisation des métallylènes avec un atome central soufré. L'effet apporté sur les métallylènes par ces nouveaux ligands sulfonimidamides a été étudié par calcul DFT. Le dernier chapitre est centré sur l'application de plusieurs complexes de ruthénium en catalyse de transfert d'hydrogène avec plusieurs substrats carbonylés. L'utilisation de stannylènes stabilisés par des ligands sulfonimidamides a été étudiée en catalyse de polymérisation de la ε-caprolactone. / This work concerns the synthesis of mixed germylene-sulfoxide ligands that were involved in coordination chemistry with several transition metals and finally applied in hydrogen transfer catalysis. In a second part, the synthesis of new metallylenes stabilized by a sulfonimidamide group was develop, which were applied in polymerization catalysis. The first chapter is centered on the state of the art of germylenes with their synthesis, their stabilization and finally their coordination chemistry and applications in catalysis. Sulfoxides will also be described for their potential as hemilabile ligands. The second chapter describes the synthesis of germylene-α-sulfoxide ligands as structurally tunable structures (cyclohexyl, tBu, tolyl..) and with different oxidation states of the sulfur atom (thioether, sulfoxide and sulfone). The coordination chemistry led to the formation of bis-germylene group IV complexes, bidentate-ruthenium and monodentate ruthenium complexes. The third chapter shows the extension of the methodology to the formation of germylene-β-sulfoxide ligands. The influence of the spacer between the two entities on the coordination chemistry was studied and shows the formation of bidentate group IV complexes. Coordination to ruthenium led to obtain a surprising bis-ruthenium complex characterized by X-ray diffraction analysis. Finally, the novel architecture allowed to obtain two nickel (0) complexes, one of them including carbonyl ligands permitting a TEP comparison. The fourth chapter is centered on the synthesis of new ligands, analogue of amidinate substituents for metallylene stabilization with a central sulfur atom. The effect brought to the metallylene center by the sulfonimidamide was studied by DFT calculations. The last chapter concerns the application of several ruthenium complexes in hydrogen transfer reaction with various carbonyl compounds. The use of sulfonimidamide stannylenes was also investigated in polymerization catalysis of ε-caprolactone.