DFT model investigations on copper(II) chloride complexes: Halogen bonding of pyridyl bromine of CuCl 2(NH 3)(NC 5H 4Br-3) with several metal ligands

Abstract

A set of theoretical model systems, investigated by the DFT method with hybrid basis sets, was utilized to mimic and exploit the halogen bond found in the neutral metal–organic coordination, CuCl 2(NC 5H 4Br-3) 2. The optimized calculations indicate that, while coordinating to metal ions, the end-bromine of organic halide subunit exhibits better directionality and affinity to electron density donors. Halogen bonding energies are substantial and range from −2.5 to −37.5 kcal/mol. These results reveal the importance of metal-influenced halogen bonding in directing supramolecular arrangements. To further study the nature of the halogen bond, the analyses of NBO and AIM were carried out. The conclusions show a considerable extent of charge transfer, complicated orbital interactions, and distinct bond critical points between interacting atoms upon halogen bonding.