نبذة مختصرة : Context.This research work focuses on the activation of diverse organic electrophiles through oxidative addition initiates numerous Pd- and Ni-catalyzed cross-coupling reactions, influenced by factors including the substrate composition, metal complex properties, solventeffects and the presence of additives. These reactions are analyzed using a DFT (Density Functional Theory) perspective. Chapter I reviews the main results regarding the OA of organic electrophiles to Pd(0) complexes, under conditions relevant for catalytic reactions. In Chapter II, based on the previous experimental work by Negishi, Amatore and Jutand. A comprehensive exploration of the fundamental mechanism behind halide salt (LiCl, Bu4NCl)-promoted the PhI oxidative addition to Pd(0) is revealed by DFT simulation: i) the chlorides promote phosphine release, leading to a mixture of mononuclear and dinuclear Pd(0) complexes. ii) Anionic Anionic Pd(0) dinuclear complexes exhibit a cooperativity between Pd(0) centers, which favors the oxidative addition of iodobenzene. iii) In the presence of Li+, the oxidative addition to mononuclear [Pd0L(Li2Cl2)] is estimated barrierless. LiCl coordination polarizes Pd(0), enlarging both theelectrophilicity and the nucleophilicity of the complex, which promotes both coordination of the substrate and the subsequent insertion into the C-I bond. These conclusions are paving the way to the rational use of the salt effects in catalysis for the activation of more challenging bonds. In Chapter III, we employ DFT level calculations and compare them with spectroscopic and kinetic data to investigate the mechanism of the Ni(COD)2 catalyzed cross-coupling of 2−methoxynaphthalene with PhLi, and assess the speciation of lithium nickelate intermediates. The significant influence of solvents and the multiples roles played by lithium on the reaction are unveiled . Further support for the calculated mechanism is derived from the identification of additional nickelate intermediates through stoichiometric reactions. Based on this ...
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