Structural characterization of two solvates of a luminescent copper(II) bis(pyridine)-substituted benzimidazole complex

Abstract

Copper(II) complexes of benzimidazole are known to exhibit biological activity that makes them of interest for chemotherapeutic and other pharmaceutical uses. The complex bis(acetato-κO){5,6-dimethyl-2-(pyridin-2-yl)-1-[(pyridin-2-yl)methyl]-1H-benzimidazole-κ2N2,N3}copper(II), has been prepared. The absorption spectrum has features attributed to intraligand and ligand-field transitions and the complex exhibits ligand-centered room-temperature luminescence in solution. The acetonitrile monosolvate, [Cu(C2H3O2)2(C20H18N4)]·C2H3N (1), and the ethanol hemisolvate, [Cu(C2H3O2)2(C20H18N4)]·0.5C2H6O (2), have been structurally characterized. Compound 2 has two copper(II) complexes in the asymmetric unit. In both 1 and 2, distorted square-planar N2O2 coordination geometries are observed and the Cu—N(Im) bond distance is slightly shorter than the Cu—N(py) bond distance. Intermolecular π–π interactions are found in 1 and 2. A weak C—H...π interaction is observed in 1.

Keywords

• crystal structure
• copper(II)
• benzimidazole
• hydrogen bonding
• π–π interactions
• C—H...π interactions