A computational study on the nature of the halogen bond between sulfides and dihalogen molecules

Abstract

The characteristics and nature of the halogen bonding in a series of B···XY (B = H2S, H2CS, (CH2)2S; XY = ClF, Cl2, BrF, BrCl, Br2) complexes were analyzed by means of the quantum theory of “atoms in molecules” (QTAIM) and “natural bond orbital” (NBO) methodology at the second-order Moller-Plesset (MP2) level. Electrostatic potential, bond length, interaction energy, topological properties of the electron density, the dipole moment, and the charge transfer were investigated systematically. For the same electron donor, the interaction energies follows the B···BrF > B···ClF > B···BrCl > B···Br2 > B···Cl2 > B···ClBr order. For the same electron acceptor, the interaction energies increase in the sequence of H2S, H2CS, and (CH2)2S. Topological analyses show these halogen bonding interactions belong to weak interactions with an electrostatic nature. It was found that the strength of the halogen-bonding interaction correlates well with the electrostatic potential associated with halogen atom and the amount of charge transfer from sulfides to dihalogen molecules, indicating that electrostatic interaction plays an important role in these halogen bonds. Charge transfer is also an important factor in the halogen bonds involved with dihalogen molecules.