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.