Synthesis and magnetism of heterobinuclear Cu(II)-Fe(II) complexes bridged by N,N′-bis(3-aminopropyl)oxamidocopper(II)

Four new mu-oxamido heterobinuclear complexes have been synthesized and characterized, namely [Cu(oxpn)Fe(L)(2)]SO4, where oxpn denotes the N,N'-bis(3-aminopropyl)oxamido dianion and L represents 1,10-phenanthroline (phen); 5-nitro-1,10-phenanthroline (NO2-phen); 5-chloro-1,10-phenanthroline (Cl-phen) and 2,2'-bipyridine (bpy). Based on the elemental analyses, spectroscopic studies, magnetic moments (at room temperature) and molar conductivity measurements, extended oxamido-bridged structures consisting of a copper(II) and an iron(II) ions, which have a square planar environment and an octahedral environment, respectively, are proposed for these complexes. The [Cu(oxpn)Fe(bpy)(2)]SO4 (1) and [Cu(oxpn)Fe(phen)(2)]SO4 (2) complexes have been characterized by variable temperature magnetic susceptibility (4.2 similar to 300 K) and the observed data were least-squares fitted to the susceptibility equation derived from the spin Hamiltonian including single-ion zero-field interaction for the iron(II) ion, (H) over cap = -2J (S) over cap(1).(S) over cap(2) - D (S) over cap(z)(2), giving the exchange integrals J = -21.8 cm(-1) for (1) and J = -23.2 cm(-1) for (2). These results are commensurate with antiferromagnetic interactions between adjacent metal ions within each molecule.