Re-examination of linewidth alternation in the electron paramagnetic resonance spectrum of the 1,4-dinitrodurene radical anion

Abstract

The EPR spectrum of the 1,4-dinitrodurene radical anion, prepared by electrochemical reduction in dimethylformamide, has been studied between 223 and 343 K. The EPR spectrum presents a classic example of linewidth alternation (first observed in 1962) and can be computer-simulated on the basis of a two- or a four-jump model. The two-jump model, in which the nitrogen atoms interchange their environment, tends to give poor reproductions of the experimental spectra. However, the four-jump model, based on the change of environment of only one nitro group during a particular jump, gives a much better fit to the experimental spectra over the complete temperature range.