CATION COMPLEX MOTION AND HYDROGEN-BONDS IN GUANIDINIUM NITRATE

Proton NMR linewidths and second moments, and spin-lattice relaxation times in the laboratory (12 and 60 MHz) and in rotating frames (H-1 = 9 x 10(-4) T) were studied for polycrystalline guanidinium nitrate ove r a temperature range covering three solid phases. An analysis of the experimental results enabled us to reveal a complex cation motion and derive the respective activation parameters. In the low-temperature ph ase a proton motion in the hydrogen bond has been demonstrated and cha racterized. A convergence of two reorientational correlation times of the guanidinium cation has been discovered at the first-order phase tr ansition.