Electron spin resonance, ENDOR and TRIPLE resonance of some 9,10-anthraquinone radicals in solution. Part 2.—Anthraquinonesulphonates

Abstract

We report studies on radical anions of 9,10-anthraquinone-1-sulphonate, 9,10-anthraquinone-1,5-disulphonate, 9,10-anthraquinone-2-sulphonate, 9,10-anthraquinone-2,6-disulphonate and 9,10-anthraquinone-1,2-dihydroxy-3-sulphonate in alkaline ethanol and water mixtures carried out by multiple resonance spectroscopy. The hyperfine coupling constants and relative signs were determined in ENDOR and TRIPLE resonance experiments. The temperature dependence of the coupling constants was measured and the g values were also estimated. Use of a modified additivity relationship suggested a new assignment of the coupling constants.