Charge density study of bis(clonixato)bis(ethanol) bis(imidazole)copper(II) complex

Abstract

Abstract An experimental electronic structure of bis(clonixato)bis(ethanol) bis(imidazole)copper(II) complex, [Cu(cln)2(im)2(EtOH)2] (cln=clonixato, im=imidazole) (1) has been obtained from single-crystal X-ray diffraction data collected at 100 K using an Incoatec IμS Ag microfocus source. Metal-ligand (ML) bonds and hydrogen bonds (HBs) have been analysed using topological analysis of the experimental electron density with the atoms in molecules (AIM) approach. The central copper atom is octahedrally coordinated by two oxygen atoms from two clonixato anions and two nitrogen atoms from two imidazole ligands in equatorial plane. In axial positions are two oxygen atoms from two ethanol molecules. AIM analysis establishes that the central copper atom is bonded more strongly to the clonixato anion that to the imidazole or ethanol molecules. AIM analysis of two intramolecular and one intermolecular hydrogen bonds permits to estimate their strength. We show that the hydrogen bonds are strong enough to protect the molecule from decomposition in solvent media and to disable the more reactive imidazole-Cu-clonixato complex from interacting with e.g. a macromolecule. The electrostatic potential of the complex shows a highly positive value on the central atom, so the complex is highly reactive in an interaction with negative ligands.