Synthesis, crystal structure and magnetic properties of novel copper(II)-nickel(II) complexes of macrocyclic oxamides

Three novel oxamido-bridged heterobinuclear copper(II)-nickel(II) complexes derived from macrocyclic oxamido compounds have been synthesized and characterized by IR, ESR and electronic spectra. They are of the formula 1(CuL1)Ni(pmtn)(NCS)ClO4 (1), [Cu(L-2)Ni(pmtn)(NCS)]ClO4 (2) and [(CuL3)Ni(pmtn)(NCS)]ClO4 (3), where H2L1 = 2,3-dioxo-5,6:14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclopentadeca-7,12-diene, H2L2 = 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene and H2L3=2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene, respectively. The crystal structure of 2 has been determined by X-ray crystallography. The nickel(II) ion is pseudo-octahedrally coordinated and the copper(II) ion is in a distorted square-pyramidal environment. The temperature dependence of the magnetic susceptibility for 1 and 2 has been analyzed using the Hamiltonian (H) over cap = -2J (S) over cap (1).(S) over cap (2), leading to J = -47.5 and -47.2 cm(-1). for 1 and 2, respectively. (C) 2001 Elsevier Science Ltd. All rights reserved.