Synthesis and magnetic properties of copper(II)-lanthanide(III) heterobinuclear complexes with N,N′-bis[3-(dimethylamino)propyl]oxamido as ligand

Nine new mu-oxamido-bridged copper(II)-lanthanide(III) heterobinuclear complexes, described by the overall formula Cu(dmoxpn)Ln(NO(2)phen)(2)(NO3)(3) (Ln=La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er), where dmoxpn denotes N,N'-bis[3(dimethylamino)propyl]oxamido dianions and NO(2)phen represents 5-nitro-1,10-phenanthroline, have been synthesized and characterized by the elemental analyses, molar conductivity measurements and spectroscopic (IR, UV, ESR) studies. The complex Cu(dmoxpn)Gd(NO(2)phen)(2)(NO3)(3) was further characterized by variable-temperature magnetic susceptibility (4.2similar to300K) measurements and the magnetic data have also been used to deduce the indicated heterobinuclear structure. The results derived from least-squares fit of the experimental data have confirmed that the adjacent copper(II) and gadolinium(III) ions through the oxamido-bridge in the complex are ferromagnetically coupled with the exchange integral J((Cu-Gd)) = +7.8 cm(-1). A plausible mechanism for the ferromagnetic coupling between gadolinium(III) and copper(II) is discussed. (C) 2004 Elsevier B.V. All rights reserved.