Radical anions of nitrobenzothiazoles. II. EPR study of free radical anions and ion pairs

The paramagnetic species produced by reduction of the title compounds (NBTZ) with different reducing agents have been characterized by EPR spectroscopy. Radical ion pairs were observed upon reduction with alkali metals (Li, Na, K) in THF only from 5-, 6-, and 7-nitrobenzothiazole. The free radical anion of 7-NBTZ was obtained by reduction with Na in HMPA. Different tetraethylammonium ion pairs of the radical anion of 7-NBTZ were detected in HMPA when the reduction was performed by electrolysis at variable concentration of tetraethylammonium perchlorate as supporting electrolyte.