Ferromagnetically coupled heterobinuclear Cu(II)‐Ln(III) complexes with N,N′ ‐bis(2‐aminoethyl)‐oxamido dianion as a bridged ligand

Six novel μ‐oxamido heterobinuclear complexes, namely Cu(oxae)Ln(Me 2 bpy) 2 ‐(ClO 4 ) 3 (LnLa, Nd, Gd, Tb, Ho, Er), where oxae denotes N, N '‐bis(2‐aminoethyl)oxamido dianion, Me 2 bpy is 4,4'‐dimethyl‐2,2'‐bipyridyl, have been synthesized and characterised by elemental analyses, IR, conductivity measurements and electronic spectra. The temperature dependence of the magnetic susceptibility of Cu(oxae)Gd(Me 2 bpy) 2 (ClO 4 ) 3 has been measured over the range 4–300 K. The least‐squares fit of the experimental susceptibilities yielded J = 1.87 cm −1 . The observed Gd(III)‐Cu(II) coupling is ferromagnetic. One plausible mechanism that can cause a ferromagnetic coupling between Gd(III) and Cu(II) is discussed in terms of spin‐polarization.