Generation, ESR Spectra, and Isolation of N-(Arylthio)-2,4,6-triarylphenylaminyl Radicals. Influence of the Substituents on the 2,4,6-Triphenyl Groups on the Stabilities of Radicals

Three N-(Arylthio)-2,4,6-tris(4-methylphenyl)-, three N-(arylthio)-2,4,6-tris(3-chlorophenyl)-, and five N-(arylthio)-2,4,6-tris(4-chlorophenyl)phenylaminyl radicals have been generated by PbO2 oxidation of the corresponding N-(arylthio)-2,4,6-triarylanilines and their isolation has been carried out. When electron-donating methyl groups were substituted at the p-positions of the 2,4,6-triphenyl groups, the aminyls were less stable, and only one could be isolated as radical crystals. On the other hand, when chloro atoms were substituted at the m- or p-positions of the 2,4,6-triphenyl groups, the aminyls were more stable and most were isolated. The isolated radical crystals were stable for a long period without any decomposition. The spin density distributions in the radicals are discussed on the basis of the ESR parameters.