Halogen bonds involved in copper(I) complexes: a study based on the electronic charge density

This communication describes crystal structures of Cu(I) complexes and their topological analysis with emphasis on the Laplacian of the electron density to investigate the characteristic of the halogen bonding (XB). To gain insight into the XBs we carried out a survey of the wave function and DFT methods. Different XBs, Cl...Cl¯, I...I¯, Br...N3¯, and I...SCN¯ in the crystal packing of these compounds, are categorized as a combination of a region of charge depletion and a region of charge concentration in valence shell charge concentration or hole−lump interactions. The full quantum potential based lump−hole concept is more useful than the σ-hole concept in which the electrostatic portion of potential is merely considered. Such a view about halogen bonding can rationalize the geometry around XBs. As well as non-covalent interaction reduced density gradient (NCI-RDG) approach were pursued to real-space visualization and quantitative investigation of the XBs.