The preparation and characterization of tetranuclear Cu-4(bnac)(4)(mu-OEt)(4) complex is described. Crystallographic characterization of this complex has shown that the co-ordination geometry around copper(H) ions is distorted square pyramidal (monoclinic, C2/c, a = 13.3980(2) angstrom, b = 14.6080(2) angstrom, c = 25.7460(4) angstrom, alpha = 90.00, beta = 103.4090(10)degrees, gamma = 90.00 degrees, V= 4901.59(13) angstrom, Z= 8). The in situ-generated Cu-2(bnac)(2)(mu-OEt)(4)(4R-py)(4) complexes were suitable catalysts for the catalytic oxidation of 3,5-DTBCH2 to 3,5-DTBQ with dioxygen at ambient condition in good yields. The catalytic activity was found to obey Michaelis-Menten type kinetics and increase with electron-releasing substituent on co-ordinated pyridines. (c) 2005 Elsevier B.V. All rights reserved.