Structural correlation of catecholase-like activities of oxy-bridged dinuclear copper(II) complexes

Eight oxy-bridged dinuclear copper(II) complexes with catecholase-like sites, [Cu(L-1)X](2) (HL1=1 -diethylaminopropan-2-ol. X=N-3(-) 1, NCO- 2, and NO2- 3), [Cu(L-2)X](2) (HL2 = N-ethylsalicylaldimine. X = NO3- 4, Cl- 5. N-3(-) 6, NCS- 7), and [Cu(L-3)](2)(ClO4)(2) 8 (HL3 =N-(salicylidene)-N'-(2-pyridylaldene)propanediamine) have been prepared and characterized. The single crystal X-ray analysis show that the structures of complexes 6 and 8 are dimeric with two adjacent copper(II) atoms bridged by pairs of CL-oxy atoms from the L-2 and L-3 ligands. Magnetic susceptibility measurements in the temperature range 4-300 K indicate significant antiferromagnetic coupling for 4, 5 and 7 and ferromagnetic coupling for 6 between the copper(II) atoms. The catecholase activity of complexes for the oxidation of 3,5-di-tert-butylcatechol by O-2 was studied and it was found that the complexes with the bond distance of Cu(II). . . Cu(II) located at 2.9-3.0 Angstrom show higher catecholase activity. (C) 2001 Elsevier Science B.V. All rights reserved.