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

Density functional investigation has been performed to explore structural and electronic properties of σ-hole bonded complexes formed from the interaction between NH3, H2O and HF as nucleophile and molecules containing σ-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 σ-hole atom the hydrogen bonding is preferred. The role of electrostatic potential in formation of σ-hole complex is also demonstrated and discussed.