Computational chemistry of organometallic and inorganic species

Abstract

This thesis presents computational investigations of problems related to redox processes and structural rearrangement in inorganic systems. Density functional theory has been used to gain insight into the origin and nature of such reactions. The work presented concerns two main topics: hydrogenase-like systems containing an Fe2 core and carbonphosphorus cluster compounds. In chapters II and III, we describe the impact of reduction, an important phenomenon in the H2 production catalytic cycle, on a hydrogenase-like model. In collaboration with Talarmin and co-workers who have conducted careful electrochemical studies, we have used DFT to identify structures of species observed in cyclic voltammetry. We have also studied the binding of a proton to similar systems and, through the calculation of chemical shifts and coupling constants, confirmed the structures of iron hydrides observed by 1H NMR spectroscopy. In chapter V we focus on carbon-phosphorus systems that can exist in 2 or more isomeric forms. We address first the case of a system of formula C6H4P3 which has the right valence configuration to exist either as a planar structure or as a 3-dimensional cluster (nido according to Wade’s rules). We then examine whether it is possible to control the preferred conformation by the addition of substituents on the phenyl ring. Finally, we look at the rearrangement of a planar diphosphene into a cage isomer and try to understand the mechanism and in particular the role of the protonation in the conversion from planar to 3-dimensional structure