<p>Smaller cellular telephones and more energy-efficient windows are just two examples of technological advances which call for new materials. Materials chemists seek to develop new materials, both out of pure curiosity to see which combination of elements and structures can be obtained and in efforts to produce materials, with specific properties. The starting materials (in solid, liquid or gaseous form) can then be combined and prepared in various ways. A chemical method that is gaining more attention for thin-film growth is Atomic Layer Deposition (ALD). This is a sophisticated type of vapor deposition in which the precursor gases are introduced separately into the reaction chamber.</p><p>Silicon carbide (SiC) and cubic boron nitride (c-BN) are extremely hard diamond-like materials, both with a high potential for application within the modern microelectronics and tool industry. Hexagonal boron nitride (h-BN), with its graphite-like layered structure, is a promising ceramics material.</p><p>Deposition of thin SiC and BN films from gaseous precursors has been studied by theoretical and experimental methods. The chemical composition and atomic arrangement of a growing surface is important for vapor growth. The surface may be terminated (e.g., by hydrogen atoms) and adopt various geometrical structures. Reconstruction of unterminated SiC(0001) surfaces, as well as H abstraction from the corresponding H-terminated surfaces, were studied using quantum mechanical calculations. Elementary reactions for vapor growth of SiC and BN, and <i>in situ</i> incorporation of dopant and contaminant species into these surfaces were also investigated theoretically. Moreover, thin films of BN were deposited by means of laser-assisted ALD. The general goal has been to predict and/or explain experimental results by investigating growth mechanisms.</p>

Smaller cellular telephones and more energy-efficient windows are just two examples of technological advances which call for new materials. Materials chemists seek to develop new materials, both out of pure curiosity to see which combination of elements and structures can be obtained and in efforts to produce materials, with specific properties. The starting materials (in solid, liquid or gaseous form) can then be combined and prepared in various ways. A chemical method that is gaining more attention for thin-film growth is Atomic Layer Deposition (ALD). This is a sophisticated type of vapor deposition in which the precursor gases are introduced separately into the reaction chamber. Silicon carbide (SiC) and cubic boron nitride (c-BN) are extremely hard diamond-like materials, both with a high potential for application within the modern microelectronics and tool industry. Hexagonal boron nitride (h-BN), with its graphite-like layered structure, is a promising ceramics material. Deposition of thin SiC and BN films from gaseous precursors has been studied by theoretical and experimental methods. The chemical composition and atomic arrangement of a growing surface is important for vapor growth. The surface may be terminated (e.g., by hydrogen atoms) and adopt various geometrical structures. Reconstruction of unterminated SiC(0001) surfaces, as well as H abstraction from the corresponding H-terminated surfaces, were studied using quantum mechanical calculations. Elementary reactions for vapor growth of SiC and BN, and in situ incorporation of dopant and contaminant species into these surfaces were also investigated theoretically. Moreover, thin films of BN were deposited by means of laser-assisted ALD. The general goal has been to predict and/or explain experimental results by investigating growth mechanisms.

Ce travail porte sur la synthèse, la caractérisation et l’évaluation en catalyse de réduction des protons en dihydrogène, de nouveaux complexes de Ni(II), Co(III), Cu(II) et Pd(II) basés sur des ligands de type thiosemicarbazone. La nature de l’espèce catalytique active a été étudiée par voltampérométrie cyclique et des propositions de mécanisme ont été formulés sur la base de calcul quantique de type DFT.Le premier chapitre introduit le contexte scientifique. Le second chapitre concerne la synthèse et la caractérisation des ligands de type N2S2 et des complexes mononucléaires associés de Ni, Cu et Pd. Le troisième chapitre présente la synthèse et la caractérisation de complexes binucléaires de Co et trinucléaire de Ni.Les études électrochimiques de ces complexes dans le DMF en présence d’une source de protons, nous a permis d’évaluer leur efficacité catalytique. Nos résultats montrent que les complexes du Cu et du Pd présentent une vague irréversible spécifique pour la réduction des protons, mais une décomposition est observée durant l’électrolyse. Par contre, les complexes de Ni et de Co ont montré une stabilité électrochimique ainsi que de bonnes performances catalytiques. En particulier, le nouveau complexe mononucléaire de Ni présente des propriétés catalytiques remarquables qui le classent parmi les meilleurs catalyseurs de la réduction des protons décrits dans la littérature. L’ensemble de ce travail fourni une description complète du comportement électrochimique des ligands de type N2S2 complexés à des métaux de transition. Il permet d’envisager des développements futurs dans l’amélioration des propriétés catalytiques de ces complexes. / This work focuses on the synthesis, the characterization and the catalytic evaluation in the reduction of protons into dihydrogen, of new complexes of Ni(II), Co(III), Cu(II) and Pd(II) based ligands Type thiosemicarbazone. The catalytically active species during the process of the proton reduction was studied by cyclic voltammetry and mechanisms were formulated on the basis quantum chemical calculation.The first chapter introduces the scientific context, the goals and the main objectives of this work. The second chapter concerns the synthesis and the characterization of the N2S2 ligands and their associated mononuclear complexes, Ni, Cu and Pd. The third chapter presents the synthesis and the characterization of binuclear Co and trinuclear Ni based on N2S2 ligand.Electrochemical studies of these complexes in DMF in the presence of a proton source (trifluoroacetic acid), allowed us to evaluate their catalytic efficiency. Our results show that Cu and Pd complexes have a specific irreversible wave for the reduction of protons, but decomposition is observed during electrolysis, which makes these uninteresting complexes for the reduction of protons.On the contrary, Ni and Co complexes showed an electrochemical stability and good catalytic performances. In particular, the new mononuclear Ni complex exhibits remarkable catalytic properties that rank it among the best catalysts for the reduction of protons reported in the literature. All this work provided a complete description of the electrochemical behavior of N2S2 thiosemicarbazone ligands complexed to transition metals. It allows considering future developments in improving the catalytic properties of these complexes.

De nos jours, la capacité à synthétiser de nouveaux catalyseurs métallique bioinspirés pour améliorer et élargir le spectre d'activité catalytique est d’une importance capitale pour une chimie respectueuse de notre environnement.Cette thèse se concentre sur la conception de nouveaux complexes de métaux de transition (cuivre et palladium) basés sur deux classes différentes de ligands organiques : les benzotriazolyle-phénolates et les phosphonates. La synthèse et la caractérisation de nouveaux composés a été réalisée par différentes méthodes physico-chimiques (électrochimie, EPR, UV-vis, IR, cristallographie aux rayons X) et la chimie théorique. La génération et la caractérisation des différentes espèces réduites et oxydées nous ont aidés dans la détermination des mécanismes possible. Les composés obtenus ont été utilisés avec succès comme catalyseurs dans divers procédés tels que: la production d'hydrogène, l'oxydation d'alcool et le clivage d'ADN. / Nowadays, the ability to synthesize new bioinspired metal catalysts to improve and broaden the spectrum of catalytic activity is of paramount importance for sustainable chemistry respectful for our environment. This thesis is focused on the design of transition metal complexes (copper and palladium) based on two different classes of organic ligands: benzotriazolyl-phenolates and phosphonates.Different original complexes based on palladium and copper were synthetized from benzotriazolyl-phenolate and phosphonates ligands. The characterization of the new compounds was performed by different physical and physico-chemical methods (electrochemistry, EPR, UV-vis, IR, X-ray crystallography) and quantum chemistry. The generation and characterization of different reduced and oxidized species helped us in the possible mechanisms determination. The obtained compounds were successfully employed as catalysts in different processes as: hydrogen production, alcohol oxidation and DNA cleavage.

This thesis presents computational studies of problems in the organic and polymer chemistry. The state-of-the art quantum chemical methods are used to gain further insight into the origin and the nature of the reactions in three different organic and polymer systems. The research questions are conceptually approached by identifying the key aspects. Then an appropriate strategy for the quantum chemical modeling is developed. In the scope of the polymer chemistry, the novel synthesis technique of nanostructured materials, the so-called twin polymerization, is investigated. Using three model systems of increasing complexity the influence of the anion (trifluoroacetate) in the reaction system is investigated. The effect of the solvent polarity as well as the effect of the entropic contributions are also considered. The rearrangement reaction of the volatile cyanotritylcarbenes is another topic. These carbenes readily rearrange to ethene main products, however also small amount of the unexpected heptafulvenes is formed. This unprecedented heptafulvene formation is modeled in detail and the energetics is systematically evaluated to identify most reasonable rearrangement pathways of the probable multiple alternative routes. Computational investigation of other tritylcarbenes with varying spectator substituents results in sophisticated data base for experimental investigations. At last, some controversial observations in experimental studies concerning the kinetics of the electrophilic alkylation of the barbiturate anion are studied. To interpret the kinetic measurements, different alkylation pathways are analyzed with respect to their energetics. Further, the influence of microsolvation is demonstrated.