N2H4 Derived Sulfonic Acids: Hydrazine Disulfonate, [(SO3)HNNH(SO3)]2−, and Hydrazine Iso‐disulfonate, [H2NN(SO3)2]2

The reaction of hydrazinium sulfate and chlorosulfonic acid in pyridine leads to the pyridinium salt of the hydrazine disulfonate anion, [(SO3)HNNH(SO3)]2−. The salt is the starting material for the preparation of further hydrazine disulfonates, for example of alkaline metals and barium. In all compounds, the [(SO3)HNNH(SO3)]2− anion adopts the gauche conformation. The conformer is chiral but all of the investigated compounds crystallize as racemates. The disulfonate anion can occur in another constitution with the two sulfonate groups attached to only one nitrogen atom. This so‐called hydrazine iso‐disulfonate, [H2NN(SO3)2]2−, has been prepared through a substitution reaction between potassium imidodisulfonate, K2[HN(SO3)2], and hydroxylamine‐O‐sulfonic acid, H2NOSO3H. The hydrazine iso‐disulfonate anion has been crystallized as potassium and barium compound, respectively. The compounds were characterized by XRD, vibrational spectroscopy, DFT calculations and thermal analyses. Insertion of SO3 molecules into the N−H bonds of hydrazine, N2H4 lead to the hydrazine disulfonate [(SO3)HNNH(SO3)]2− and the hydrazine iso‐disulfonate, [H2NN(SO3)2]2− anion, respectively. The salts of these new anions have been characterized comprehensively, including thermal analyses, Raman spectroscopy and DFT calculations.