Theoretical studies of traditional and halogen-shared halogen bonds: the doped all-metal aromatic clusters MAl3 − (M = Si, Ge, Sn, Pb) as halogen bond acceptors

Abstract

In this paper, ab initio MP2 calculations have been performed to study the traditional and halogen-shared halogen bonds formed by a series of doped all-metal aromatic clusters MAl3 (-) (M = Si, Ge, Sn, Pb) and YX (Y = HCC-, F3C-, HO-; X = Cl, Br, I). On the basis of our calculations, four halogen-bonded interaction modes, coded as MAl3 (-)-XY-1, MAl3 (-)-XY-2, MAl3 (-)-XY-3 and MAl3 (-)-XY-4, have been recognized for complexes of MAl3 (-)-XY. In particular, the configurations (configurations 2 and 3) of the HCCX- and F3CX-containing complexes display different arrangements from those of HOX-containing complexes. Although the most positive electrostatic potentials on the surfaces of X atoms in monomers of YX (Y = HCC-, F3C-, HO-; X = Cl, Br, I) are similar, the interaction strength of HOX-containing complex is much stronger than those of HCCX- and F3CX-containing complexes. Based on the AIM, NBO and ELF analyses, the halogen bonds in the HCCCl/Br- and F3CCl/Br-containing complexes belong to traditional halogen bonds, while those in SiAl3 (-)-BrCF3-1, GeAl3 (-)-BrCF3-1 and HCCI- and F3CI-containing complexes are halogen-shared halogen bonds. The halogen bonds in the HOX-containing complexes belong to covalent bonds or halogen-shared halogen bonds.