SYNTHESIS AND MAGNETIC-PROPERTIES OF MU-OXAMIDO COPPER(II) BINUCLEAR COMPLEXES

Four binuclear complexes have been synthesized, namely [Cu(oxae)Cu(L)(2)] (ClO4)(2), where oxae denotes the N,N'-bis(2-aminoethyl)oxamido dianion and L denotes 2,2'-bipyridyl (bpy), 4,4'-dimethyl-2,2'-bipyridyl (Me(2)bpy), 1,10-phenanthroline (phen) and 5-nitro-1,10-phenanthroline (NO2-phen). Based on IR, elemental analyses, conductivity measurements, electronic spectra and crystal structure of a similar complex, the complexes are proposed to have oxamido-bridged structures and to consist of two copper(II) ions in a distorted square-pyramidal environment. The complexes have been characterized by variable-temperature magnetic susceptibility and the susceptibility data were least-squares fit to the susceptibility equation derived from the spin Hamiltonian (H) over cap = -2J (S) over cap(1).(S) over cap(2). The exchange integral, J, was found to be equal to -208 cm(-1) for bpy (75-300 K), J = -204 cm(-1) for Me(2)bpy (75-300 K) and J = -225 cm(-1) for NO2-phen (4.2-300 K). These results are commensurate with strong antiferromagnetic interaction between the adjacent metal ions.