Thermal decomposition of compounds containing the hydrazinium cation as a ligand

A thermal investigation of M(N₂H₅)₂(SO₄)₂, where M = Mn(II) or Co(II), has been carried out. On heating, the complexes become MSO₄ via an intermediate compound, M(N₂H₄)_0·5(HSO₄)(SO₄)_0·5. The intermediate compound has been isolated and characterised by elemental analyses, IR spectra, diffuse reflectance spectra, magnetic and conductance data. The intermediate compound seems to possess pseudo-tetrahedral coordination where one SO₄ group is tetradentate and bonded with four different metal ions which are surrounded by HSO₄ groups and hydrazines bridging two metal ions. The X-ray powder diffraction pattern of the intermediate derived from the cobalt(II) complex has been obtained and the d-values are reported. Activation energies (E^*) and enthalpy changes (ΔH) for each decomposition step have also been calculated. The probable mechanisms of decompositions are discussed.