Raman Spectroscopic Discovery of the Hydrogenthiosulphate Anion, HSSO3 -, in Solid NH4HS2O3 [1]

Reaction of ammonium thiosulphate with concentrated sulphuric acid in anhydrous methanol at —80°C affords [NH4][HS2O3] the anion of which was shown by Raman spectroscopy to have the structure HSSO3 - (stretching vibrational wavenumbers: SS = 403, SH = 2486, SO = 1027, 1183, and 1219 cm-1; SSH bending mode = 873 cm-1 at —80°C). This salt decomposes at —20°C to give, inter alia, elemental sulfur. The Raman spectra of ND4DS2O3 and (NH4)2S2O3 are also reported.