Novel halogen bonding interactions between MH2 (M = Mg, Be) and HX (X = Cl, Br, I) molecules

Junming Lu, Yunxiang Lu, Weiliang Zhu

a b s t r a c t

In this work, a systematic theoretical investigation on a series of dimeric complexes formed between MH2
and HX has been carried out by employing correlated ab initio methods. It was shown that besides dihydrogen
bonds, there also exists novel noncovalent X  H interactions between the two molecules, which
have similar characteristics to traditional halogen bonds. Upon complexation, the HAX bonds tend to
elongate in all cases, concomitant with red-shifts of the HAX stretching frequencies. X  H interaction
energies, calculated at the MP2/aug-cc-pvtz level, range from 2.11 to 11.78 kJ/mol; the interactions
are much weaker than corresponding dihydrogen bonds. The major stabilization source of dihydrogen
and halogen bonds arises from the electrostatic force, while charge-transfer force plays a minor role in
the formation of the complexes. AIM analyses further confirm the presence of X  H interactions in the
systems, and the electron density at bond critical points correlates fairly well with the interaction energy.