Inequivalent Reorientation of the Trichloromethyl Groups in 1,4-Bis(TrichloromethyI) Benzene as Studied by Pulsed 35Cl NQR

The temperature dependence of T of Cl NQR of the title com pound evidenced that the three crystallographically inequivalent CCl groups have different potential barriers against reorientation (about 30, 36, and 42 kJ/mol). An intramolecular interaction between π-electrons on the benzene ring and the C -Cl bond is proposed to interpret the characteristic frequency splitting common to the Cl NQR spectrum of each of the three inequivalent CCl groups. The magnitude of T 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 frequency can be interpreted by reorientation.