Proton spin-lattice and spin-spin relaxation times of (N(CH3)3)H)(I)(TCNQ)

Proton spin-lattice T(1) and spin-spin T(2) relaxation times are reported for (N(CH(3))(3)H)(I)(TCNQ) in the temperature range 150 to 5OOK. The overall relaxation process of the system can be described by contributions from rotation of the N(CH3)3H+ group about its symmetry axis, tumbling of that group, and the scalar and dipole interactions of the protons with the unpaired electron. Rotation of the trimethylammonium group leads to a minimum in T(1) at 21OoK, while tumbling gives rise to another minimum at 340°K. The activation energies for the two processes are 0.064 and 0.11 eV, respectively. The overall reorientation of the N(CH(3))3,H+ group, therefore, appears to dominate the T(1) process below 400°K. No direct evidence is observed in the NMR data for the reversible transition seen in the conductivity and ESR data at 16O(o)K, however, it does appear that such a transition may influence the N(CH(3))(3),H+ reorientations leading to smaller activation energies for the reorientation processes.