Generation, ESR Spectra, and Isolation of N-(Arylthio)-4-t-butyl-2,6-diphenylphenylaminyl Radicals

Oxidation of N-(arylthio)-4-t-butyl-2,6-diphenylanilines yields quite persistent and oxygen-insensitive N-(arylthio)-4-t-butyl-2,6-diphenylphenylaminyls which, in solution, give a characteristic blue, purple, or wine-red color. Among the aminyls generated, N-(4-nitrophenylthio)-4-t-butyl-2,6-diphenylphenylaminyl is isolated as radical crystals. The ESR spectra are split into a simple 1 : 1 : 1 triplet by the interaction with a nitrogen nucleus. Upon deuteration of the phenyl groups at the 2 and 6 positions of the anilino group, the 1 : 1 : 1 triplets are split further by the interaction with the meta protons of the anilino group and the ortho protons of the arylthio group. The spin density distribution in the radical is discussed on the basis of the hyperfine coupling constants.