An NQR study of the thermally activated motion of nitro groups in 3-nitrobenzene sulphonyl chloride

A study of the temperature dependence of the 35Cl NQR frequency and linewidth, and the 35Cl and 37Cl spin-lattice relaxation times, in 3-nitrobenzene sulphonyl chloride (3:NO2- phi -SO2Cl) is reported. The pressure dependence of the 35Cl frequency is also reported. The latter measurements indicate the existence of a first-order phase transition induced by pressure. It is shown that all the results are consistent with the onset of reorientations of NO2 groups. The parameters deduced, including the activation energy, are compared with those obtained from previous studies of 2:NO2- phi -SO2Cl and 4:NO2- phi -SO2Cl.