Synthesis and properties of 1,3-diphenyl-5-(benzothiazol-2-yl)-6-R-verdazyls

Novel 1,3-diphenyl-5-(benzothiazol-2-yl)-6-R-verdazyls, stable free radicals, were synthesized from the corresponding formazans by alkylation followed by cyclization and oxidation of the intermediate leucoverdazyls (yields 78–93%). The radicals were characterized by ESR, electronic and IR spectroscopy, mass spectrometry, X-ray diffraction (for one of them) and cyclic voltammetry. The resulting verdazyls are stable under ordinary conditions and are reduced more readily but more difficult to oxidize than the triphenylverdazyl analogue.