Synthesis, characterization, spectroscopic studies and toxicity analysis of heterobinuclear complexes of Mn(ii), Co(ii), Ni(ii) and Cu(ii) ions

Abstract

Heterobinuclear complexes of transition metal ions with 5-nitroindazole in the presence of bis-(1,2-diaminobenzene)malonyldihydrazone Cu(II)/Ni(II) chloride of the type [M1L1M2(L2)2Cl2] where M1=Cu(II), Mn(II), Co(II), M2=Cu(II) Ni(II), L1=bis-(1,2-diaminobenzene)malonyldihydrazone L2=5-nitroindazole, have been prepared. All of the complexes have been characterized by IR, UV-Vis and EPR spectroscopy, elemental analysis, magnetic moments and molar conductance measurements. Spectral studies and molar conductance measurements in DMF suggested the covalent nature of the complexes. An square planar geometry is proposed for M1 and octahedral for M2 for the binuclear complexes. The lowering of the magnetic moment values and overlapping of the EPR signal are due to spin crossover since both of the metals have unpaired electrons with the same molecular symmetry. The lowering of the magnetic moment has been discussed. The toxicity of the representative compounds has been studied against cockroaches. The Ni(II) complexes are more toxic than the Cu(II) complexes.