Spectral, thermal, and X-ray studies on some new bis and tris-hydrazine and hydrazinium metal pyruvates

Some bis-hydrazine metal pyruvates of transition metal ions of the formula MCH₃COCOO]₂ N₂H₄]₂, where M = Co, Ni, Zn or Cd, tris-hydrazine metal pyruvates of the formula MCH₃COCOO]₂ N₂H₄]₃, where M = Co, Ni, Zn or Cd, and hydrazinium metal pyruvates N₂H₅]₂MCH₃COCOO]₄, where M = Co or Ni have been prepared and the compositions of the complexes have been determined by chemical analysis. The magnetic moments and electronic spectra of the complexes suggest a high-spin octahedral geometry for them. Infrared spectral data of bis-hydrazine complexes indicate the bidentate bridging mode shown by hydrazine molecules and mono dentate coordination by pyruvate ions. However, in tris-hydrazine complexes the pyruvate ions are ionic in nature. In hydrazinium complexes two hydrazinium ions and four pyruvate ions show unidentate coordination mode resulting in six coordination around metal ions. Thermo gravimetry and differential thermal analysis in air reveal that most of the complexes decompose in one step to give the respective metal carbonate as the final residue. However, the hydrazinium complexes yield Co₂O₃ or NiO as the residue. The final residues were identified by their X-ray powder data. The X-ray powder diffraction patterns of each series of complexes reveal isomorphism among the series.