ESR studies of free radicals derived from hydroxyquinones. II. Group 14 adducts of hydroxyanthraquinones and some phosphorus adducts of chrysazin

The reactions of Group 14 metal-centred radicals with 9,10-anthraquinone, 1,4-anthraquinone, and eight hydroxy-substituted 9,10-anthraquinones have been investigated by ESR spectroscopy. The results are discussed in terms of the regioselectivity of the addition reaction, the influence of hydroxyl substituents on the electron spin density distribution, and the effect of varying the Group 14 metal from silicon through to lead. 1,8-Dihydroxyanthraquinone (chrysazin) gives unusually persistent adducts with Group 14 metal-centred radicals and is also a spin-trap for phosphorus-centred radicals. © 1988.