Dimethoxyhydroxycarbenium hexafluorometallate -: Synthesis, spectroscopic characterization and the crystal structure of (MeO)2COH+SbF6-

Dimethyl carbonate reacts in the superacidic system HF/MF5 (M = As, Sb) with formation of (MeO)(2)COX+MF6- (M = As, Sb; X = H, DJ. (MeO)(2)COH+SbF6- crystallizes in the orthorhombic space group Pna2(1) (No. 33) with a = 9.668(2) Angstrom, b = 8.340(2) Angstrom, c = 11.135(4) Angstrom and four formula units per cell. The unit cell contains (MeO)(2)COH+ cations of approximate C-s symmetry with an almost central trigonal planar CO3 skeleton and C-O bond lengths in a range between 1.26(1) Angstrom and 1.30(2) Angstrom. The salt contains long O-H and Sb-F bond and an FH contact of 1.62(9) Angstrom. With regard to the formation of the salts, the reaction of dimethyl carbonate with the superacidic systems XF/MF5 (X = H, D; M = As, Sb) is discussed and the Raman, IR, H-1 and C-13 NMR spectra of (MeO)(2)COX+MF6- (M = As, Sb; X = H, D) are reported.