Molecular Motion Studied by Proton Magnetic Resonance in a [N(CH3)4]2ZnCl4 Single Crystal

The proton NMR line width and spin–lattice relaxation times for [N(CH3)4]2ZnCl4 single crystal were studied over a wide temperature range. Proton spin–lattice relaxation time measurements on [N(CH3)4]2ZnCl4 yielded a minimum, which were attributed to the effect of molecular tumbling. It seems obvious that the high-temperature minima of T1 is attributable to the tumbling motion of [N(CH3)4] ions, and that the T1 below 161 K is attributable to the same molecular motion which dominates at 210 K. Then, the T1 below 161 K undergoes a slow motion. The activation energies in phase VI and IV were determined to be 13.94 and 22.49 kJ/mol, respectively.