INEQUIVALENT REORIENTATION OF THE TRICHLOROMETHYL GROUPS IN 1,4-BIS(TRICHLOROMETHYL) BENZENE AS STUDIED BY PULSED CL-35 NQR

The temperature dependence of T1 of Cl-35 NQR of the title compound ev idenced that the three crystallographically inequivalent CCl3 groups h ave different potential barriers against reorientation (about 30, 36, and 42 kJ/mol). An intramolecular interaction between pi-electrons on the benzene ring and the C-Cl bond is proposed to interpret the charac teristic frequency splitting common to the Cl-35 NQR spectrum of each of the three inequivalent CCl3 groups. The magnitude of T2 of each Cl atom is interpreted by intra- and intermolecular H...Cl interactions. It was found that only part of the temperature dependence of the NQR f requency can be interpreted by reorientation.