Synthesis and Structure of Protonated Sulfur Dioxide

Salts of protonated sulfur dioxide were synthesized by recrystallization of [FS(OX)2][SbF6] (X=H, D) in aprotic solvents at low temperatures. Hemiprotonated sulfur dioxide [(SO2)2H][Sb2F11] was obtained from the solvent SO2 and the monoprotonated sulfur dioxide [OSOD][Sb2F11], using 1,1,1,2-tetrafluoroethane as solvent. For both compounds, single crystals were obtained and an X-ray structure analysis was conducted. Furthermore, the salts were characterized by Raman spectroscopy and the results were discussed together with quantum chemical calculations on the M06-2X/aug-cc-pVTZ level of theory. Hemi- and monoprotonated SO2 cations have been isolated as Sb2F11- salts. The preparation of the salts was achieved by recrystallization of [FS(OH)2][SbF6] in weakly basic, aprotic solvents at low temperatures. The elusive structures of both cationic species have been investigated by X-ray structure analysis and Raman spectroscopy.+ image