Radical-anions of cyclopentadithiophenones and dithienothiophen 7,7-dioxides. Electron spin resonance spectra and polarographic halfwave reduction potentials

Abstract

The e.s.r. spectra of the radical-anions of cyclopentadithiophenones, generated by electrolysis in acetonitrile and (or) dimethylformamide, and of three dithienothiophen 7,7-dioxides, produced by potassium reduction in dimethoxyethane, have been recorded. Assignment of the hyperfine splitting constants is based on the hyperfine splitting constants of deuteriated derivatives. The polarographic half-wave reduction potentials of cyclopentadithiophenones were determined in dimethylformamide. Cyclopentadithiophenones appear to be reduced by a reversible one-electron transfer in the first reduction step. An attempt to relate the hyperfine splitting constants to computed spin densities by Hückel–McLachlan calculations is only partially successful.