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

Proton and fluorine NMR second moments and spin-lattice relaxation tim es of polycrystalline guanidinium hexafluorozirconate and its deuterat ed analogue were studied in laboratory (60 MHz) and rotating (H-1 = 20 G) frames over a wide range of temperature. An analysis of the experi mental results enabled us to reveal a dynamical inequivalence of two c rystallographically independent cations and an unexpected high mobilit y of nonspherical anion dimers. A comparison of the ions dynamics in 2 :1 complex studied with the guanidinium 1:1 and 3:1 complexes has show n a significant contribution of the hydrogen bonds to the potential ba rriers hindering the anion reorientations. At low temperatures a proto n motion in the hydrogen bond and at 400 K a solid-solid phase transit ion have been discerned.