Solvation spectra. Part 22.—Effect of ionic association on the electron spin resonance spectrum of 2,6-Dimethyl-p-benzosemiquinone

Abstract

The electron spin resonance spectra of a range of ion-pairs of 2,6-dimethyl-p-benzosemiquinone in t-pentanol and 1,2-dimethoxy-ethane show that the cation favours the oxygen atom remote from the methyl groups. In some instances, marked line broadening occurs which can be interpreted in terms of intramolecular interconversion between the isomeric ion pairs, as also can the disproportionate broadening of the outer lines arising from hyperfine coupling to cation nuclei. The spectra which arise for various rates of interconversion are contrasted with the more familiar situation of interconversion of equivalent structures present in equal concentrations. The spectra of various ion-pairs of 2,6-di-t-butylbenzosemiquinone and 2,6-dichlorobenzosemiquinone are also reported and discussed.