Bonding studies of dinuclear transition metal bis(μ-η2-silane) complexes [LnM(μ-η2-HSiR2)]2 by density functional theory

The bonding and structural features of a series of dinuclear transition metal bis(μ-η2-silane) complexes [LnM(μ-η2-HSiR2)]2 were studied using density functional theory calculations. These dinuclear complexes consist of two metal fragments doubly bridged by two (μ-η2-HSi) units with a formal metalmetal bond. Each metal fragment conforms to either the 16- or 18-electron rule dependent on the spatial arrangement of ligands around each metal coordination sphere. These dinuclear silane complexes display noticeably shorter Si⋯H distances in the [M(μ-η2-HSi)]2 units when compared with mononuclear η2-silane complexes. The shorter Si⋯H distances in the metal–(η2-silane) interactions suggest that these dinuclear complexes are more non-classical than mononuclear ones. The more non-classical feature is a result of weaker metal(d) to SiH(σ*) back-donation interactions due to the presence of a metal substituent at silicon.