Is a transition metal–silicon quadruple bond viable?

Abstract

Quadruple bonding in heavier main group elements is not known albeit having four valence orbitals accessible for bonding. Here we report the unprecedented quadruple bonding between a silicon atom and a transition metal fragment in the ¹A₁ electronic ground state of C_3v symmetric SiRu(CO)₃ based on high level theoretical calculations. Various bonding analyses reveal the nature of the SiRu quadruple bonding interaction, which involves one usual Si–Ru σ bond, two usual Si–Ru π bonds and one additional Si → Ru dative σ bond.