¹H NMR Study of Ionic Motions in High Temperature Solid Phases of (CH₃NH₃)₂ZnCl₄

The reorientation of the tetrahedral complex anion ZnCl₄^2- and the self-diffusion of the cation in (CH₃NH₃)₂ZnCl₄ were studied by ¹H NMR spin-lattice relaxation time (¹H T₁) experiments. In the second highest-temperature phase, the temperature dependence of ¹H t₁ observed at 8.5 MHz could be explained by a magnetic dipolar-electric quadrupolar cross relaxation between ¹H and chlorine nuclei, and the activation energy of the anion motion was determined to be 105 kJ mol^-1. In the highest-temperature phase, the activation energy of the self-diffusion of the cation was determined to be 58 kJ mol^-1 from the temperature and frequency dependence of ¹H T₁.