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Ces travaux de thèse portent sur le développement de catalyseurs à base de ligands carbène N-hétérocycliques dérivés de fer et de nickel, deux métaux de transition abondants, pour les réactions de hydrosilylation et de borylation. Le premier chapitre porte sur les travaux réalisés à l’aide de complexes de fer du type [Cp(NHC)Fe(CO)₂][X] (X = I, PF₆) possédant des ligands de type benzimidazole ou imidazole et leur évaluation en hydrosilylation de dérivés carbonylés. Le deuxième chapitre traite de l’utilisation de complexes demi-sandwichs de nickel du type CpNi(NHC) en hydrosilylation d’aldéhydes, de cétones, d’aldimines et de cétimines. Enfin le troisième chapitre est consacré à la réaction de borylation catalysée par des complexes de nickel demi-sandwich CpNi(triazole)X et des complexes de nickel possédant deux ligands chélatants anioniques de type carbene N-hétérocyclique fonctionnalisé par un bras amido. / The research work described in this manuscript has for main objective the development of new homogeneous catalytic systems based on N-heterocyclic carbene (NHC) iron and nickel complexes for hydrosilyation and borylation reactions. The first chapter describes the use of [Cp(NHC)Fe(CO)₂][X] (X = I, PF₆) complexes bearing benzimidazole or imidazole NHC type ligands for hydrosilylation of benzaldehyde and acetophenone. In a second chapter, we have shown that half-sandwich NHC-nickel complexes in the presence of a catalytic amount of NaHBEt3 can be efficient catalysts for the reduction of aldehydes, ketones, aldimines and ketimines in the presence of diphenylsilane. In the last chapter, two new series of non-classical NHC-nickel triazole complexes had been developed: (i) one series with half sandwich NHC-nickel triazole complexes and (ii) another one based on chelating anionic amido-functionalized N-heterocyclic carbene nickel complexes. The two series of complexes were then evaluated in catalytic borylation cross coupling reaction.

Platinum(II) complexes [(NHC)Pt(L)] with various β-diketonate based auxiliary ligands (L: 3-meacac = 3-methylacetylacetonato, dpm = dipivaloylmethanato, dbm = dibenzoylmethanato, mesacac = dimesitoylmethanato, duratron = bis(2,3,5,6-tetramethylbenzoyl)methanato) and a C^C* cyclometalated N-heterocyclic carbene ligand (NHC: dpbic = 1,3-iphenylbenzo[d]imidazol-2-ylidene, dpnac = 1,3-diphenylnaphtho[2,3-d]imidazol-2-ylidene or bnbic = 1-phenyl-3-benzylbenzo[d]imidazol-2-ylidene) were found to show different aggregation and photophysical properties depending on the auxiliary ligand. Eight complexes were prepared from a silver(I)–NHC intermediate by transmetalation, cyclometalation and subsequent treatment with potassium-tert-butanolate and β-diketone. They were fully characterized by standard techniques including ¹⁹⁵Pt NMR. Five complexes were additionally characterized by 2D NMR spectroscopy (COSY, HSQC, HMBC and NOESY). Solid-state structures of five complexes could be obtained and show the tendency of the square-planar compounds to form pairs with different Pt–Pt distances depending on the bulkiness of the substituents at the auxiliary ligand. The result of the photophysical measurements in amorphous PMMA films reveals quantum yields of up to 85% with an emission maximum in the blue region and comparatively short decay lifetimes (3.6 µs). Density functional theory (DFT/TD-DFT) calculations were performed to elucidate the emission process and revealed a predominant ³ILCT/³MLCT character. Organic light-emitting devices (OLEDs) comprising one of the complexes achieved 12.6% EQE, 11.9 lm W⁻¹ luminous efficacy and 25.2 cd A⁻¹ current efficiency with a blue emission maximum at 300 cd m⁻². The influence of an additional hole-transporter in the emissive layer was investigated and found to improve the device lifetime by a factor of seven.