Thermodynamic activation parameters of hindered rotation of the CF3 group in the 4-nitrophenyltrifluoromethylsulfone radical anion in DMF

Abstract

The thermodynamic activation parameters of hindered rotation of the CF3 group in the 4-nitrophenyltrifluoromethylsulfone radical anion in DMF were determined from the temperature dependence of the EPR line widths and spin density distributions calculated by the U-B3LYP method in the 6-31+G* basis set. In the range 293 > T > 199 K, the activation energy of hindered rotation EF depends on the temperature and changes in the range 9.67 < EF < 18.95 kJ·mol−1; the changes in the activation enthalpy and entropy are 7.23 < ΔH≠ < 17.30 kJ·mol−1 and −53.45 < ΔS≠ < −11.37 J·(mol·K)−1, respectively. Based on the suggested method for evaluating the inner product of the g tensor and the tensor of anisotropic hfi with the 14N nucleus for nitrobenzene radical anions in the liquid state we calculated the correlation time and determined the activation energy of rotational diffusion of the 4-nitrophenyltrifluoromethylsulfone radical anion in DMF, Er = 20.175±0.54 kJ·mol−1.