Cu(II) complexes with tridentate sulfur and selenium ligands: catecholase and hydrolysis activity

Two new copper(ii) mononuclear complexes (C(Se)andC(S)) were synthesized and characterized by the following techniques: X-ray crystallography, elemental analysis, IR, EPR and UV-vis spectroscopies, conductimetric analysis and mass spectrometry. The crystalline structures of both complexes revealed two neutral complexes pentacoordinated with their chalcogenated ligands coordinating to the copper(ii) center in a tridentate way with Se, N, Se and S, N, S as donor atoms and twocis-chloro ions completing the coordination structures. The hydrolytic activity in phosphate diester cleavage ofC(Se)andC(S)was investigated using 2,4-BDNPP as a substrate, and applying the Michealis-Menten approach, giving the kinetics parameters (C-Se/C-S):k(cat)(s(-1)) = 1.17 x 10(-4)/1.97 x 10(-4);K-M(mol L-1) = 3.13 x 10(-3)/5.58 x 10(-3). Both complexes also catalyze the oxidation of the 3,5-di-tert-butylcatechol (3,5DTBC) substrate with turnover numbers of 4.32 x 10(-2)s(-1)forC(Se)and 4.87 x 10(-2)forC(S).