ENDOR and ESEEM studies of ion radicals of artificial dimethoxy- or halogen-1,4-benzoquinones with an alkyl side chain of differing length

Abstract

ENDOR measurements of anion radicals of artificial dimethoxy- or halo-1,4-benzoquinones with an alkyl side chain of differing length in solution yield a number of proton isotropic hyperfine constants. Analysis of the constants obtained gives the orientation of substituents relative to the quinone plane. ESEEM measurements of the ion radicals in frozen solutions of deuteriated solvents indicate that the cation, but not the anion, radicals experience a strong interaction with solvent deuterium, which is hydrogen bonded to the quinone oxygen.