Syntheses and magnetic properties of O-phenylenebis(oxamato)-bridged CoIICuIICoII complexes

Four new heterotrinuclear complexes have been prepared and characterized, namely {Co(L)2]2Cu (opba)]}(ClO4)2, where opba=o-phenylenebis(oxamato) and L=1,10-phenanthroline (phen), 5-nitro-1,10-phenanthroline (NO2-phen), 2,2-bipyridyl (bpy) and 4,4-dimethyl-2,2-bipyridyl (Me2bpy). The temperature dependence of the magnetic susceptibility of {Co(phen)2]2Cu(opba)]}(ClO4)2 has been studied in the 4–300K range, the MT versus T plot exhibits a minimum at ca. 131K, but abnormal magnetic behaviour below 83K.