Synthesis, characterization and thermal properties of sodium pyruvate thiosemicarbazone and some of its metal complexes

The Schiff base sodium pyruvate thiosemicarbazone (SPTSC) was synthesized from the condensation of sodium pyruvate and thiosemicarbazide hydrochloride in aqueous medium. This molecule coordinates to a variety of divalent metal ions M2+ (M = Fe, Co, Ni, Cu or Cd) and one type of complexes was obtained with general formulae [M (SPTSC)2]. The modes of bonding and overall geometry of the complexes were determined through physicochemical and spectroscopic methods. These studies revealed octahedral geometry of all prepared complexes. Thermal analyses (TG and DTG) of (SPTSC) and all complexes have been carried out to confirm the final molecular structures of free ligand and its metal complexes and also to study their thermal stability. This study confirms that the complexes have been formed by the coordination of metal ion to the (SPTSC) donor atoms only (there is no coordinate and hydrate solvents). Also the study shows that the prepared complexes have more thermal stability than free ligand (SPTSC) and the thermal stability of (SPTSC) has been enhanced by the coordination to metal ions.