Free-radical studies by resonance Raman spectroscopy. Photochemically generated N-substituted benzidine cation radicals

The free-radical cations of benzidine, [2H4]benzidine and N,N,N′,N′-tetramethylbenzidine have been formed by u.v. photolysis of the neutral parent compounds trapped in clear glassy ethanol matrices at 77 K. The radicals all have intense visible absorption bands which facilitate excitation of their resonance Raman spectra. These Raman spectra have been assigned and interpreted in terms of structural changes from the corresponding parents.