Stabilization of sulfenyl(poly)selenide ions in N,N-dimethylacetamide
Abstract
Whereas redox processes resulted from the reactions PhSe−/S8 or PhSe2Ph/S3˙−, mixed anions RSSey− (R = Ph, PhCH2; y = 1–3) were obtained by the slow addition of solid selenium to thiolate ions in N,N-dimethylacetamide. The RS− + n Se reactions, which were investigated by spectroelectrochemistry, led initially (n = 1) only to the formation of RSSe− ions. These species oxidized into RS2R faster than RS− on a gold electrode, with the simultaneous electrodeposition of very reactive microcrystals of selenium. On a preparative scale, the substitution of RSSe− ions (R = CH3, Ph) on alkyl halides yielded RSSeR′ compounds (R′ = PhCH2, CH3, respectively) which greatly disproportionated. Further additions of Se (n = 2, 3) to RS− ions led to RSSe2− and RSSe3− in equilibrium with RS2R and mixtures of Sex2− polyselenide ions (x = 4,6; 6,8). Visible spectra of RSSe2− and RSSe3− ions were calculated from the study of the backward reactions RS2R + Sex2− (x = 4, 6).