Bridging ability of a novel polydentate ligand (H2L) comprising an oxime function.: Structures of a mononuclear precursor [NiL] and a dinuclear CuII2 complex.: Magnetic properties of mononuclear (NiII and CuII), dinuclear (CnII2, NiII2, NiIICuII and CuIICrIII) and trinuclear (CuII3, CuIIMnIICuII and CuIIZnIICuII) complexes

A novel non-symmetrical polydentate Schiff base ligand 3-({2-[(1-methyl-3-oxobut-1-enyl)amino]ethyl}imino)-butan-2-one oxime (H2L) comprising an oxime function among various donor sites yields neutral [(NiL)-L-II] and [(CuL)-L-II] complexes. The structural determination of [NiL] confirms the deprotonation of the oxime function. The deprotonated oxime oxygen atom can react with auxiliary complexes to give homo-and hetero-di-and tri-nuclear entities. The structural determination of a homodinuclear copper complex clearly shows the presence of the expected oxime bridge, along with an unexpected ketonic bridge between the two copper centres leading to a Cu[O,NO]Cu core. A moderate antiferromagnetic interaction is present in the di-and tri-nuclear copper complexes. A similar interaction is also observed in the heteronuclear complexes ((CuNiII)-Ni-II and (CuMnII)-Mn-II) and, more surprisingly, in the heterodinuclear (CuCrII)-Cr-II entity. A generalization of the Cu[O,NO]Cu structure leads to a justification of these magnetic properties.