Computational studies of the geometric and electronic structures of BF 3+, AlF 3+, CF 32+ and SiF 32+

Abstract

The title cations have been studied computationally using spin-unrestricted B3LYP hybrid density functional theory and Møller–Plesset and coupled cluster ab initio approaches. In all cases bar B3LYP BF 3 +, the equilibrium geometry is found to be of planar C 2v symmetry with one long and two short element–fluorine bonds. The ab initio calculations determine this geometry to be substantially more stable than the alternative D 3h structure. Mulliken and atoms-in-molecules analyses support the assertion that the unique element–fluorine bond is appreciably weaker than the shorter E–F bonds, in agreement with our previous experimental conclusions.