An electron spin resonance investigation of the 2-pivaloyl-1,4-benzoquinone radical anion

Abstract

The 2-pivaloyl-1,4-benzoquinone radical anion has been prepared both by electrochemical reduction (in dimethylformamide) and by alkali-metal reduction (in tetrahydrofuran). The e.s.r. spectrum observed in dimethylformamide is that of a single species. However, in tetrahydrofuran the nature of the spectra depend on the alkali-metal counter-ion. For example, linewidth variation is observed when K⁺ is the counter-ion whilst two separate species are observed when Li⁺ is the counter-ion. The results of these experiments indicate that the various species result from different locations of the alkalimetal counter-ion adjacent to the radical anion rather than from rotational conformers resulting from the rotation of the pivaloyl group.