Investigation of the hydrogen, halogen and pnicogen dimers by means of molecular face calculated by ab initio method

The noncovalent interactions, including hydrogen, halogen and pnicogen bonds, are widely known due to their significant role in both chemical reactions and biological phenomena. In this work, the potential acting on an electron in a molecule (PAEM) is introduced to present the strength and regioselectivity of noncovalent interaction. The PAEM height of noncovalent bonds, D pb , can characterize the strength of the interaction, which has the linear relationships with noncovalent binding distances and binding energies. Here, we employ the molecular face theory (MFT) based on the PAEM to visualize reactive sites for the monomers in noncolvalent bond complexes. The electron density extremes on the molecular face (MF) regarded as the local reactivity descriptor are applied to exhibit the regioselectivity and preferred direction for monomers in hydrogen, halogen and pnicogen binding complexes, in good agreement with the chemical convention and ab initio calculation results. And the overlap distances of MF between dimers have been proposed and obtained to evaluate the strength of noncovalent interaction. The MFT provides a new way to demonstrate the regioselectivity and can be applied to larger and other type molecules in the future.