Temperature-dependent hyperfine coupling constants in electron spin resonance. Part 4.—Out-of-plane vibrations of the ring protons in the cation of p-phenylenediamine

Abstract

The effect of out-of-plane vibrations on the temperature coefficient of the coupling constant of the ring protons in the radical cation of p-phenylenediamine is considered. In accordance with an earlier suggestion by the authors it is found that this mechanism adequately accounts for the experimental values of da^H_CH/dT in four different solvents.