A Theoretical Study of the Half-Sandwich Silicon(II) Cation [(Me5C5)Si]+ and of the Cationic Complex [(Me5C5)Si (DME)

Abstract

Ab-initio calculations have been performed for the half-sandwich cation [(Me5C5)Si]+ and its DME complex [(Me5C5)Si(DME)]+. For these cations, the ground state energies, the complexation energy, the frontier orbitals, the vertical singlet-triplet excitation energies, and the natural atomic charges have been calculated. In both cations, the “lone-pair” at silicon does not represent the HOMO. The nature of the weak dative O → Si bond can best be described in terms of electrostatic and attractive dispersion interactions. The DME coordination destabilizes the cluster orbitals and slightly enhances the positive charge at silicon.