The Origin of the σ-Hole in Halogen Atoms: a Valence Bond Perspective

Abstract

A detailed Valence Bond-Spin Coupled analysis of a series of halogenated molecules is here reported, allowing to get a rigorous ab initio demonstration of the qualitative models previously proposed to explain the origin of halogen bonding. The concepts of σ-hole and negative belt observed around the halogen atoms in the electrostatic potential maps are here interpreted by analysis of the relevant Spin Coupled orbitals.

Keywords: halogen bonding; intermolecular interactions; quantum mechanics; spin-coupled method; valence bond theory.