H-1 AND F-19 NMR-STUDY OF CATION AND ANION MOTIONS IN GUANIDINIUM FLUOROANTIMONATES

Proton and fluorine NMR linewidths, second moments, and spin-lattice r elaxation times of polycrystalline [C(NH2)(3)]2SbF5 and C(NH2)(3)SbF6 were studied in a wide temperature range. For the pentafluoroantimonat e, C-3-reorientation guanidinium cation and C-4-reorientation of the S bF5 anion were revealed and their activation parameters determined. Th e dynamical inequivalence of the two guanidinium cations was evidenced . For the hexafluoroantimonate, two solid-solid phase transitions were found. In the low temperature phase the guanidinium cation undergoes C-3 reorientation while the SbF6 anion reorients isotropically. The re spective activation parameters were derived. Ar high temperatures new ionic plastic phases were evidenced.