A NUCLEAR-MAGNETIC-RESONANCE STUDY OF MOLECULAR-MOTION IN SOLID TRIS(N-PROPYLAMMONIUM)ENNEACHLORODIANTIMONATE(III) (N-C3H7NH3)(3)SB2CL9

Proton magnetic resonance second moment and spin-lattice relaxation ti me were carried out on polycrystalline tris (n-propylammonium) enneach lorodiantimonate (III), (n-C3H7NH3)(3)Sb2Cl9, in the temperature range of 10-370 K. The second moment measurements show that the structure i s not rigid on the NMR scale at 10 K, the lowest temperature studied, and that CH3 and NH3 groups execute rotations about C-3 axis. The prot on spin-lattice relaxation measurements reveal two minima due to the m otions of the amino and methyl groups. Analysis of the relaxation data yields the activation energy barriers of 11.0 kJ mol(-1) and 5.8 kJ m ol(-1), respectively, for the NH3 and CH3 groups' motion. NMR data con firm the phase transition at T-c = 232 K, known from different studies . (C) 1997 Elsevier Science B.V.