• ab initio calculations;
  • protonated dimethyl sulfoxide;
  • superacid systems;
  • vibrational spectroscopy;
  • X-ray diffraction


Dimethyl sulfoxide (DMSO) reacts with the superacidic solutions of XF/MF5 and XF/GeF4 (X=H, D; M=As, Sb) under formation of the corresponding salts [(CX3)2SOX+]MF6 and [(CH3)2SOH+]4Ge3F164−, respectively. The salts are characterized by vibrational and NMR spectroscopy, and in the case of [(CH3)2SOH+]4Ge3F164− also by single-crystal X-ray analysis. The salt [(CH3)2SOH+]4Ge3F164− crystallizes in the monoclinic space group P21/c with two formula units in the unit cell. The crystal structure possesses an unusual anion consisting of a chain of three slightly distorted fluorine-bridged GeF6 octahedra. The vibrational spectra are compared to the quantum chemically calculated free [(CX3)2SOX+] cations. The described salts are isolated examples of completely protonated DMSO molecules in the condensed phase.