A study of activated molecular motion in 2-nitrobenzene sulphonyl chloride by NQR

Abstract

A comprehensive chlorine nuclear quadrupole resonance study of the temperature and pressure dependences of frequency, line width and spin-lattice relaxation time in 2-nitrobenzene sulphonyl chloride is reported. The results show that each of the two substituted groups on the benzene ring contributes to the spin-lattice relaxation via a different and independent mechanism. In the high-temperature regime, the data are successfully explained assuming reorientation of the SO2Cl group between unequal potential wells and field gradient fluctuations resulting from reorientations of nearby NO2 groups. The activation energy of both motions and the fraction of the electric field gradient influenced by the motion of nitro groups have been estimated, as well as the pressure dependence of the activation enthalpy and the activation volume for these motions.