QTAIM Characteristics of Halogen Bond and Related Interactions

Different types of noncovalent interactions such as, for example, halogen bond, hydrogen bond, and dihalogen bond are analyzed. The analysis is based on ab initio calculations which were performed on complexes of the F₃CCl molecule. This choice is connected with the features of the Cl atom which may act as the Lewis acid and also as the Lewis base center. Such a dual role is a consequence of the existence of negative and positive regions of the electrostatic potential of the Cl center. Hence, the F₃CCl molecule forms complexes linked by various interactions. The formation of the complexes leads to the electron charge redistribution which is reflected in the quantum theory of atoms in molecules (QTAIM) characteristics. Numerous correlations and tendencies were found here between QTAIM, geometrical and energetic parameters. It was found that the mechanism of the formation of complexes linked through various interactions is generally the same as that known for the hydrogen bond formation. The dependencies and QTAIM characteristics considered here are in agreement with Bent's rule