Theoretical studies on the nature of bonding in σ-hole complexes

Density functional investigation has been performed to explore structural and electronic properties of sigma-hole bonded complexes formed from the interaction between NH3, H2O and HF as nucleophile and molecules containing sigma-hole atom of groups V-VII. It is found that the strength of interaction decreases in the order of Cl > S > P and Br > Se > As. This interaction is comparable or even stronger than the normal hydrogen bonding, however in the case where the nucleophile is not aligned in proper orientation with respect to the sigma-hole atom the hydrogen bonding is preferred. The role of electrostatic potential in formation of sigma-hole complex is also demonstrated and discussed. (C) 2008 Elsevier B.V. All rights reserved.