Theoretical investigations of the H•••π and X (X = F, Cl, Br, I)•••π complexes between hypohalous acids and benzene

The H center dot center dot center dot pi and X (X = F, Cl, Br, I)center dot center dot center dot pi interactions between hypohalous acids and benzene are investigated at the MP2/6-311++G(2d,2p) level. Four hydrogen-bonded and three halogen-bonded complexes were obtained. Ab initio calculations indicate that the X center dot center dot center dot pi interaction between HOX and C6H6 is mainly electrostatically driven, and there is nearly an equal contribution from both electrostatic and dispersive energies in the case of XOH-C6H6 complexes. Natural bond orbital (NBO) analysis reveals that there exists charge transfer from benzene to hypohalous acids. Atom in molecules (AIM) analysis locates bond critical points (BCP) linking the hydrogen or halogen atom and carbon atom in benzene.