Halogen bonds and other noncovalent interactions in the crystal
structures of 1,2-diiodo alkenes: an ab initio and QTAIM study
Abstract
A series of interatomic interactions interpretable as halogen bonds
involving I…I, I…O, and I…C(π), as well as the
noncovalent interactions I…H and O…O were observed in the
crystal structures of 1,2-diiodoolefins dimers according to ab initio
calculations and the quantum theory of “atoms in molecules” (QTAIM)
method. The interplay between each type of halogen bond and other
noncovalent interactions was studied systematically in terms of bond
length, electrostatic potential and interaction energy, which are
calculated via ab initio methods at the B3LYP-D3/6-311++G(d,p) and
B3LYP-D3/def2-TZVP levels of theory. Characteristics and nature of the
haologen bonds and other noncovalent interactions, including the
topological properties of the electron density, the charge transfer and
their strengthening or weakening, were analyzed by means of both QTAIM
and “natural bond order” (NBO). These computational methods provide
additional insight into observed intermolecular interactions and are
utilized to explain the differences seen in the crystal structures.