Formation and characterization of 1-substituted 1,2-dithiolanyl radicals by laser flash photolysis

Photolyses of 1-alkylthio-3-propanethiols, 1,3-propanedtthiol and 1-phenylthio-3-propanethiol in acetonitrtle, 2-propanol or aqueous mixtures of these solvents lead to five membered cyclic sulfuranyl radicals of the type (left[ {R - overline {S - S - CH_2 - CH_2 - C} H_2 } right]) which exhibit characteristic uv/vis absorption spectra. These 1-substituted 1,2-dithiolanyl radicals are formed by intramolecular cyclization of the primarily formed thiyl radicals generaeed by S-H- bond cleavage in the excited starting material. The wavelength of the absorption maximum observed for these transients depends on the natuee of the substituntt R on the sulfur atom (R=H, alkyl, aryl).