Synthesis and Characterization of Metal Complexes with Mercaptosuccinic Acid and Hydrazine as Ligands

摘要

Reaction of hydrazine and mercaptosuccinic acid with metal ion forms complexes with general formula, (M(N2H4)2{CH2(COO)CH(COOH) (S)}]·(H2O)_n where n = 1 when M = Hg(II), Pb(II), n = 2 when M = Zn(II), Cd(II) and n = 3 when M = Co(II) at pH 4. The acid shows dianionic nature showing deprotonation in one of the -COOH groups and in -SH group in these complexes. The complexes have been characterized by analytical, IR and UV-visible spectroscopy and thermal studies. IR spectra show N-N stretching frequencies in the region 985-935 cm~(-1) indicates the nature of hydrazine in the complexes. Simultaneous TG-DTA analysis indicates that hydrazine complexes of Co(II), Cd(II), Pb(II) undergo endothermic dehydration in the range of 90-105 °C followed by exothermic dehydrazination in the temperature range, 238-282 °C and exothermic decomposition in the range of 290-467 °C to the respective metal sulfide/sulfates as the end product. Zn complex shows a different thermal degradation pattern resulting in zinc oxide as an end product. SEM images and XRD pattern of the end products show that they are of nano size. X-Ray powder diffraction patterns show isomorphism among the complexes with similar molecular formulae. The kinetic parameters of the complexes have been computed by Coats-Redfern equation.