Metal Sulfite Hydrazine Complexes

The synthesis of metal sulfite hydrazine complexes involves two steps. Firstly, hydrazine hydrate (99-100%) is saturated with SO2 gas and the resulting product, hydrazinium sulfite monohydrate (N2H5)2S03-H20, is 

Secondly, metal sulfite hydrazines are obtained by the treatment of (N2H5)2S03-H20 with divalent metal ions (M = Fe, Mn, Co, Ni, or Zn) [19]. 

1 Metal Sulfite Hydrazines [MS03-xN2H yH20] 

Metal sulfite hydrazines are synthesized using hydrazinium sulfite monohydrate under different preparative conditions as mentioned below [20]. 

A calculated quantity of (N2H5)2S03-H20 is dissolved in N2H4 H2O to obtain an alkaline solution of pH 9. To this, a stoichiometric quantity of metal salt (M) solution (M SO3 = 1 1) in aqueous solution is added with constant stirring. The compound formed is initially washed with alcohol and then dried in vacuum desiccator over P2O5. 

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The combustion of mixed metal sulfite hydrazine complexes in the presence of air (—300 °C) gives homogenous ferrites (Table 3.18). This is confirmed by the observed weight loss and powder XRD. 

The composition of metal sulfite hydrazine hydrate complexes is established by chemical analysis. Infrared absorption spectra of the compounds are identical and show characteristic absorption frequencies of N2H4 and sulfite (Table 3.16). 

Similar to hydrazinium metal sulfates, hydrazinium metal sulfite complexes can be synthesized the procedure is, though, slightly different. Hydrazinium transition metal sulfite dihydrate complexes of the formula (N2H5)2M(S03)2(H20)2 where M = Fe, Co, Ni, Cu, and Zn are prepared from metal hydrazine carboxylates (described in Chapter 4) as the starting material. In this method, the anhydrous metal hydrazine carboxylate, M(N2H3C00)2, is added to distilled water previously saturated with sulfur dioxide gas. The complex decomposes with the liberation of carbon... 

The prepared mixed metal hydrazine hydrates are light in color and insoluble in water. From the chemical analysis it is evident that all mixed metal complexes, including magnesium, are present as sulfite [21]. However, when magnesium alone is used without FeS04, a bisulfate hydrazine is obtained under the same preparative conditions. 

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