THE SYNTHESIS, SPECTROSCOPIC AND THERMAL STUDY OF OXAMIC ACID COMPOUNDS OF SOME METAL(II) IONS

The preparation of oxamic acid complexes of general formula M(H2NCOCOO )(2) . xH(2)O (M = Mn-II, Co-II, Ni-II, Cu-II or Zn-II; x = 1 for Cu-I I, x = 2 for the other metals) is reported. The i.r. and Raman spectra are discussed considering a trans-octahedral structure, formed by fiv e-membered chelate rings with the amide oxygen and one carboxylic oxyg en as donor atoms. The apical positions are occupied by water molecule s. The thermal degradation process is very similar for the different c omplexes, first losing H2O in one or different steps, then the fragmen ts of the organic ligand to give the metal oxide as residue. The therm al degradation of the Cu-II and Zn-II compounds results in the formati on of a new polymeric compound by deprotonation of the primary amide f unction in an endothermic process, the polymer further decomposes to f orm the metal oxide.