Synthesis, Infrared Spectra, and Thermal Properties

The dihydrazinium cation ((N2H5)2 ) being a dicationic species forms salts with dibasic acids of the type H2B. Salts that are generated from the dihydrazinium cation are prepared by the reaction of ammonium salts with hydrazine hydrate [8, 10]. 

A typical synthesis of dihydrazinium sulfite (N2H5)2S03 is described here. Apart from the above method, one can also start its synthesis with hydrazinium sulfite hydrate. This salt is obtained by the reaction of SO2 with N2H4-H20. 

Anhydrous dihydrazinium sulfite is obtained by dehydration of the hydrated salt [(N2H5)2S03-H20] in a vacuum desiccator over phosphorus pentoxide at room temperature. The formed sulfite is characterized by IR spectra where a peak around 960 cm corresponding to t N-N stretching confirms the formation of the dihydrazinium salt. 

To prepare a carbonate salt of the dihydrazinium cation by the route (2.13), where ammonium carbonate is dissolved in hydrazine hydrate. Notably, when this reaction is attempted, instead of a carbonate salt of hydrazine being formed a viscous, syrupy liquid is obtained. The liquid has been shown to be hydrazinium hydrazine carboxylate (N2H5COON2H3) [23]. This occurs because commercial ammonium carbonate is a mixture of ammonium bicarbonate and ammonium carbamate (NH4HCO3 NH2COONH4). The probable reaction is shown below  

Several hydrazonium salts that are known to exist with inorganic anions of the formula N2Hg(A)2 or N2H6B, where A is a monovalent anion, like halide, NO3, and CIO4, while B is divalent anion such as C2O4, SO4, and so on [1,4]. 

---

Budukuley, J.S. and Patil, K.C. (1990) Synthesis, infrared spectra and thermoanalytical properties of transition metal sulphite hydrazine hydrates. Journal of Thermal Analysis, 36, 2583-2592. 

Because of their low solubility, most lanthanide sulfite phases have been prepared only as amorphous or polycrystalline powders. As a result, their structural characterization is incomplete and based mainly on the interpretation of infrared spectra. In the past, studies on lanthanide sulfites have been directed mainly to the synthesis and identification of binary and more complex ternary sulfites. As well, there are a few studies dealing with solubility and solution equilibria. In more recent years, the emphasis has been on thermal properties. 

---