The crystal structures of two novel polymorphs of bis­­(oxonium) ethane-1,2-di­sulfonate

Two novel crystal forms of bis(oxonium) ethane-1,2-disulfonate, 2H3O- C2H4O6S2 2, are reported. Polymorph II has monoclinic (P21/n) symmetry, while the symmetry of form III is triclinic (P1). Both structures display extensive networks of O—HO hydrogen bonds. While this network in Form II is similar to that observed for the previously reported Form I [Mootz & Wunderlich (1970). Acta Cryst. B26, 1820–1825; Sartori et al. (1994). Z. Naturforsch. 49, 1467–1472] and extends in all directions, in Form III it differs significantly, forming layers parallel to the ab plane. The sulfonate molecule in all three forms adopts a nearly identical geometry. The other observed differences between the forms, apart from the hydrogen-bonding network, are observed in the crystal density and packing index