Effect of the carbon atom coordination on the thermoactivated motion of the carbon-bonded trichloromethyl group

The reorientational motion of the trichloromethyl group depending on the environment of the carbon atom is considered based on the chlorine-35 nuclear quadrupole resonance (NQR) data. The study is performed for CCl3 groups bonded to tri- and tetracoordinated carbon atoms in the crystalline compounds CCl3CCl=NR (R = CH2C6H5 and CCl3CCl3) and CCl3CXClN=CClC6H4NO2-n (X = H and Cl).35Cl NQR studies of thermoactivated motion in 70 solid trichloromethyl-containing compounds are summarized. The ranges of activation energies of CCl3 reorientations at tri- and tetracoordinated carbon atoms were determined to be 10-50 and 30-90 kJ/mole, respectively, the activation energy being markedly greater in the latter case. CCl3 reorientations may be completely frozen by the bulky substituents which may be present along with CCl3 in the tetracoordinated carbon bonds.