Comparative insight into the halogen bonding of 4-chloropyridine and its metal [Cu~I, Zn~(II)] coordinations with halide ions: A theoretical study on M-C-X?X′

摘要

The M-C-X?X′ halogen bond may be considered as a novel supramolecular synthon for prediction and design of polymeric metal frameworks. In this work, a set of theoretical models, consisting of two series of complexes PyCl?X (PyCl = NC_5H_4Cl-4; X = F-, Cl-, or Br-) and MPyCl?X (M = Cu~+, Zn~(2+)), was utilized to reveal features of M-C-X?X′. To explore the influence of metal centers, a detailed comparison of the properties in PyCl?X and MPyCl?X complexes was carried out. The results showed that, while coordinating to metals, interaction energies and charge transfers exhibit a remarkable increase, which have been rationalized by analyses of electrostatic potential and density difference function. Furthermore, the individual energy contributions were examined through the symmetry-adapted perturbation theory, and the results indicated that the dominant energy contribution emerges from the electrostatic and induction energy, and the electrostatic term presents a higher increment than other energy components.