Spectroelectrochemical characterization of polyselenide ions in N,N-dimethylacetamide

Polyselenide ions formed by the reduction of variable amounts of electrodep osited selenium on a gold grid cathode have been studied in N,N-dimethylace tamide by voltammetry coupled with UV-visible absorption spectrophotometry. Grey selenium reduces in three successive steps to the stable ions Se-8(2- ) (lambda(max) = 648, 453, 398 and 260 nm), Se-6(2-) (lambda(max) = 598, 44 0 and 260 nm) and Se-4(2-) (lambda(max) = 550, 417, 307 and 260 nm). Temper ature and concentration effects gave no evidence to suggest the dissociatio n of Se-x(2-) species, in particular Se-6(2-) --> Se-3(.-).