Chemical origin of contracted C–Cl bonds in the halogen-bonded complexes

Abstract

In this paper, we calculated a series of halogen-bonded complexes. The halogen bond donor is CF_nH_3−nCl, and the halogen bond acceptors are NH₃, H₂O, H₂S, and Br⁻. Ten stable halogen-bonded complexes were obtained and the C–Cl bond length was contracted in all of these complexes. We carried out AIM and NBO analysis under the MP2/aug-cc-PVDZ optimized structures. The variation of the electron density at the bond critical point of C–Cl bond correlates well with Δr(C–Cl). A balance among intra- and inter-hyperconjugation and rehybridization determined the contracted C–Cl bond.