Modulating spin delocalization in conjugated nitroxides: 2-(N-aminoxyl-N-tert-butyl)-benzothiazole

The first controlled synthesis of the title radical, 1, was achieved by oxidation of a hydroxylamine precursor; the radical itself can thus readily be isolated, studied by ESR and UV–vis, and compared to results of computational modeling. The benzothiazole ring induces substantial delocalization of the nitroxide spin density (a(NO) = 9.2 G, a(ring N) = 2.7 G, about 10% more than is seen in the benzimidazole nitroxide analog.