Synthesis and Magnetic Properties of Heterobinuclear Copper(II)-Manganese(II) Complexes with N, N'-Bis[2-(dimethylamino)ethyl]oxamide as Ligand

Four new copper(II)-manganese(II) heterobinuclear complexes bridged by N,N - bis[2-(dimethylamino)ethyl)]oxamido dianion (dmoxae) and end-capped with 2,2 -bipyridine (bpy); 4,4 -dimethyl-2,2 -bipyridine (Me2-bpy); 5-chloro-1,10-phenanthroline (Cl-phen) or 5-bromo-1,10-phenanthroline (Br-phen), respectively, namely, [Cu(dmoxae)MnL2](ClO4)2 (L = bpy, Me2-bpy, Cl-phen, Br-phen), have been synthesized and characterized by elemental analyses, IR and electronic spectra studies and molar conductivity measurements. The electronic reflectance spectrum indicates the presence of exchange-coupling interaction between bridging copper(II) and manganese(II) ions. The cryomagnetic measurements (4.2-300 K) of [Cu(dmoxae)Mn(bpy)2](ClO4)2 complex demonstrated the operation of an antiferromagnetic interaction between the adjacent manganese(II) and copper(II) ions through the oxamido-bridge within the complex. On the basis of spin Hamiltonian, H = 2JS S 1 2 , the magnetic analysis was carried out for the complex and the spin-coupling constant (J) was evaluated as -36.9 cm-1. The influence of methyl substituents in amine groups of the bridging ligand on magnetic interactions between the metal ions of this kind of complexes is also discussed.