Heterocyclic free radicals. Part VI. Substituent effects on the distribution of the spin density in 10-arylphenoxazine and 10-arylphenothiazine cation radicals

An examination of the e.s.r. spectra of >50 cation radicals derived from 10-arylphenoxazines and 10-arylphenothiazines shows that the spin distribution is influenced essentially inductive by the aryl substituent for substituents other than p-alkylamino-groups. The variations in spin distribution are correlated using established substituent constants and it is concluded that the radicals do not deviate significantly from the geometry previously adduced for the cation radicals of 10-phenylphenoxazine and 10-phenylphenothiazine. When the aryl substituents are p-alkylamino-groups, the spin distribution and probably also the geometry of the radicals are markedly perturbed from that in the respective 10-phenylazine cation radicals.