Chemical Bonding in Transition Metal Complexes with Beryllium Ligands [(PMe3)2M−BeCl2], [(PMe3)2M−BeClMe], and [(PMe3)2M−BeMe2] (M = Ni, Pd, Pt)†

Abstract

The equilibrium geometries and bond dissociation energies of the 14 valence electron (VE) complexes [(PMe(3))(2)M-BeCl(2)], [(PMe(3))(2)M-BeClMe], and [(PMe(3))(2)M-BeMe(2)] with M = Ni, Pd, and Pt have been calculated using density functional theory at the BP86/TZ2P level. The nature of the M-Be bond was analyzed with the NBO charge decomposition analysis and the EDA energy decomposition analysis. The theoretical results predict the equilibrium structures with a T-shaped geometry at the transition metal where the PMe(3) ligands are in the axial positions. The calculated bond dissociation energies show that the M-E bond strengths are in the range of donor-acceptor complexes of divalent beryllium compounds with ammonia. The bond strength decreases when the substituent at beryllium changes from Cl to CH(3). The NBO analysis shows a negative charge at the BeX(2) fragment, which indicates a net charge flow from the transition metal fragment to the beryllium fragment. The energy decomposition analysis of the M-Be bonds suggests two donor-acceptor bonds with sigma and pi symmetry where the transition metal fragment is a double donor with respect to the beryllium ligand. The pi component of the [Ni]-->BeXX' donation is much smaller than the sigma component.