Proton magnetic relaxation and internal rotations in tetramethylammonium cadmium chloride

摘要: Proton spin–lattice relaxation times (T1) and second moments (M2), at 14.7 MHz, have been investigated for tetramethylammonium cadmium chloride. Discontinuities in T1 104 119 K indicate the occurrence of crystallographic transformations. It is proposed that, low temperature phase below K, correlation time hindered motion one methyl groups somewhat different from that other three. Using this model, calculated M2 values are satisfactory agreement with experimental data. For phase, activation energies ion, 2.0±0.3 1.6±0.3 kcal/mole (8.4±1.3 6.7±1.3 kJ/mole), considerably lower than 5.5–11 observed halides. In high energy decreases even further to 0.7±0.2 (2.9±0.8 kJ/mole). This decrease accordance order–disorder transitions involving tetrahedral ions.