C-13 CP MAS NMR-STUDY OF THE LAYERED COMPOUNDS [C6H5CH2CH2NH3](2)[CH3NH3]N-1PBNI3N+1 (N =1, 2)/

C-13 CP/MAS NMR spectra were measured on the layered compounds [C6H5CH 2CH2NH3](2)[CH3NH3]n-1PbnI3n+1 (n = 1, 2). The linewidth of the resona nce peak corresponding to the phenyl carbons changed with temperature. The maximum broadening took place at 363 K for both compounds. The ac tivation energy E(a) for the reorientation of the phenyl group was det ermined to be 25 kJ mol(-1) for n = 1 and 26 kJ mol(-1) for n = 2. The frequency factor tau(0) was evaluated from the linewidth at 363 K. Th e value of the second moment, estimated from the maximum linewidth, wa s interpreted by assuming a 180 degrees flip of the phenyl group aroun d its two-fold axis. The similarity of the activation energies for the reorientation of the phenyl group suggested that the local structure and the molecular motion of the organic cations is little affected by the difference in the sub-structure of the inorganic layer in those co mpounds.