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

Copper(II) complexes of benzimidazole are known to exhibit biological activity that makes them of inter-est for chemotherapeutic and other pharmaceutical uses. The complex bis-(acetato-κ O ){5,6-dimethyl-2-(pyridin-2-yl)-1-[(pyridin-2-yl)meth-yl]-1 H -benzimidazole-κ2 N 2 , N 3 }copper(II), has been prepared. The absorption spectrum has features attributed to intra-ligand and ligand-field transitions and the complex exhibits ligand-centered room-temperature luminescence in solution. The aceto-nitrile monosolvate, [Cu(C2 H3 O2 )2 (C20 H18 N4 )]·C2 H3 N ( 1 ), and the ethanol hemisolvate, [Cu(C2 H3 O2 )2 (C20 H18 N4 )]·0.5C2 H6 O ( 2 ), have been structurally characterized. Compound 2 has two copper(II) complexes in the asymmetric unit. In both 1 and 2 , distorted square-planar N2 O2 coordination geometries are observed and the Cu-N(Im) bond distance is slightly shorter than the Cu-N(py) bond distance. Inter-molecular π-π inter-actions are found in 1 and 2 . A weak C-H⋯π inter-action is observed in 1 .