Solvomorphism and catecholase activities of bis(μ-phenoxido) dicopper(II) complexes

Two phenoxido bridged dinuclear Cu(II) complexes, [Cu-2(L-1)(2)(NCO)(2)] (1), and [Cu-2(L-2)(2)(NCO)(2)]center dot 2CH(3)OH (2), have been synthesized using the tridentate reduced Schiff-base ligands 2-[(2-dimethylamino-ethylamino)-methyl]-phenol (HL1) and 2-[(2-diethylamino-ethylamino)-methyl]-phenol (HL2) respectively. Re-crystallization of compound 2 from dichloromethane produced desolvated complex [Cu-2(L-2)(2)(NCO)(2)] (3). The compounds 2 and 3 are pseudopolymorphs or solvomorphs which differ in the crystal system (orthorhombic, Pbca for 2 and monoclinic, P2(1)/n for 3). The complexes have been characterized by X-ray structural analyses and spectroscopic methods. In all three complexes Cu(II) is penta-coordinated having the geometry intermediate between distorted square pyramid and trigonal bipyramid with Addison parameter (tau)= 0.33, 0.48 and 0.53 for I, 2 and 3 respectively. Using 3,5-di-tert-butylcatechol (3,5-DTBC) as the substrate, the catecholase activity of complexes 1 and 2 has been studied in methanol solution; compound 2 shows slightly higher catecholase activity (k(cat) = 98.4 h(-1)) than compound 1 (k(cat), = 64.2 h(-1)). (C) 2013 Elsevier Ltd. All rights reserved.