SYNTHESIS, CHARACTERIZATION, AND TOXICITY OF HETEROBINUCLEAR COMPLEXES OF TRANSITION METAL IONS

Abstract

Heterobinuclear complexes of transition metal ions with 5-nitroindazole in the presence of bis(1,2-diaminoethane)Cu(II)/Ni(II) chloride of the type [ML₂Cl₂M′(en^*)₂] or [FeL₂Cl₂M′(en^*)₂]Cl where M = Cu(II), Mn(II), Co(II), M′ = Cu(II), Ni(II), L = 5-nitroindazole, en* = deprotonated ethylenediamine have been prepared. All of the complexes have been characterized by IR, UV-Vis and EPR spectroscopy, elemental analyses, magnetic moments and molar conductance measurements. Spectral studies and molar conductance measurements in DMF suggest the covalent nature of the complexes, except the [FeL₂Cl₂M′(en^*)₂]Cl complexes which are 1:1 electrolyte. An octahedral geometry is proposed for M and square-planar geometry for M′ 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 % mortality in terms of LD₅₀ has been evaluated. The Ni(II) containing complex is more toxic than the Cu(II) complex.

ACKNOWLEDGMENTS

We thank Indian Institute of Technology, Delhi for providing FTIR spectral facilities, the Department of Physics, Aligarh Muslim University, Aligarh for EPR spectral studies, the Tata Institute of Fundamental Research, Mumbai for the NMR sepectral facility and the Third World Academy of Science, Trieste, Italy for financial support through Research grant 98-176 RG/CHE/AS.