Metal malate hydrazinates - Precursors to fine particle oxide materials

Metal complexes of malate with hydrazine possessing the stoichiometries, M(mal).2N(2)H(4), (where M = Co, Ni and Zn and mal = -OOC-CHOH-CH2-COO-), Cd(mal).2N(2)H(4).2H(2)O and their solid solutions, M1/3Co2/3(mal).2N(2)H(4) (where M = Ni or Zn) have been prepared and characterised by various physico-cheinical techniques. Infrared spectral features show that the hydrazine moieties and the anion are present as bridging bidentate ligands. Though the complexes exhibit different decomposition behaviour, the final step of decomposition is exothermic in all the cases. On decomposing the respective solid solution precursors, the cobaltite spinels, MCo2O4 (M = Ni or Zn are formed. These precursors decompose exothermically at low temperatures (250-380 degrees C) to give the respective spinel oxides through malate intermediates. The IR spectra of the oxides are characteristic of AB(2)O(4) spinels. Fine particle nature of these spinels is evident from X-ray line broadening.