Novel Halogen-Bonded Complexes H3NBH3•••XY (XY = ClF, ClCl, BrF, BrCl, and BrBr): Partially Covalent Character

Quantum chemical calculations have been performed to study the interaction of H3NBH3 with dihalogen molecules XY (XY = CIF, ClCl, BrF, BrCl, and BrBr) at the MP2/aug-cc-pVTZ level. It is shown that a halogen-hydride halogen bond is formed between the two molecules, in which the sigma electron of the B-H bond in H3NBH3 acts as the electron donor. The strength of the halogen bond ranges from 14.82 kJ/mol in H3NBH3-ClCl complex to 40.13 kJ/mol in H3NBH3-BrF complex at the CCSD(T)/aug-cc-pVTZ level, which is comparable to medium strong hydrogen bonds. The B-H and X-Y bonds are elongated with a concomitance of a red shift. The analyses of natural bond orbital and atoms in molecules have been carried out to understand the nature of properties of this novel interaction. The results show that this interaction has partially covalent character.