Synthesis, X-ray crystallography and electrochemistry of three novel copper complexes with imidazole-containing hydantoin and thiohydantoins

Abstract

The reactions of imidazolemethylene-substituted thiohydantoins with copper(II) chloride yield three kinds of complexes with different copper coordination mode. Binuclear complexes Cu2(L1-H)2Cl2 (5), Cu2(L2-H)2Cl (6) and polymeric complex [Cu(L2-H)Cl(H2O)]n (7) (L1=(4Z)-2-thioxo-4-[(1-methyl-1H-imidazol-2-yl)methylene]-1-allylimidazol-5(4H)-one, L2=(4Z)-2-thioxo-4-[(1-methyl-1H-imidazol-2-yl)methylene]-1-(n-propyl)imidazol-5(4H)-one) were synthesized and characterized by X-ray diffraction, IR and UV–Vis spectroscopy, and cyclic voltammetry. The crystal structures of homovalent dicopper(II,II) complex 5, mixed-valence [Cu+1.5, Cu+1.5] complex 6 and polymeric copper(II) complex 7 were refined from X-ray powder and single crystal data. Complexes 5–7 undergo eight-step quasi-reversible electrochemical reduction at +0.42 to −2.23V to stable intermediates, which do not dissociate into free ligand and metal in the conditions of cyclic voltammetry experiments.