Bifurcated halogen bonds: An ab initio study of the three-center interactions

Ab initio calculations at the MP2(full)/aug-cc-pvdz level of theory have been performed to explore the nature of bifurcated or three-center halogen bonds. It has been shown that the three-center interactions in the chlorine-containing complexes are very weak, whereas the interactions in the bromine-containing complexes are relatively stronger. Bifurcated halogen bonds, where single intermolecular contacts are much longer than those of the two-center halogen bonds, exhibit weaker bond strength as compared to the two-center ones. The topological parameters obtained by means of Bader's atoms in molecules (AIM) theory have also been applied for the analysis of these interactions.