Structure, magnetic properties and catecholase activity study of oxo-bridged dinuclear copper(II) complexes

Abstract

Six alkoxy-bridged dinuclear copper(II) complexes with catecholase-like sites, [Cu(L 1)(NCS)] 2 ( 1), [Cu(L 2)(CH 3CO 2)] 2·2H 2O ( 2), [Cu(L 3)(NCO)] 2 ( 3), [Cu(L 4)(NCS)] 2 ( 4), [Cu(L 5)(NCS)] 2 ( 5), and [Cu(L 4)(Cl)] 2 ( 6), where HL 1=2-(hydroxymethyl)-pyridine, HL 2=6-methyl-2-pyridine-methanol, HL 3=2-(2-hydroxyethyl)-pyridine, HL 4=1-dimethylamino-2-methyl-1-propanol, and HL 5=1-dimethylamino-2-propanol, respectively), have been prepared and characterized. The single crystal X-ray analysis show that the structures of complexes 1– 6 are dimeric with two adjacent copper(II) atoms bridged by pairs of μ-oxy atoms from the alkoxyl group of the ligands. Magnetic susceptibility measurements in the temperature range 2–300 K for complexes 1– 6 indicate significant antiferromagnetic coupling between the copper(II) atoms. The kinetic studies on catecholase activity of complexes for the oxidation of 3,5-di- tert-butylcatechol by O 2 was studied and it found that the complexes with the bond distance of Cu(II)⋯Cu(II) located near 2.98 to ∼2.99 Å show high catecholase activity. The reaction rate constant for the catecholase activity was obtained by Michaelis–Menten model.