Naphthalene-1,2,3-Dithiazolyl and Its Selenium-Containing Variants

Synthetic routes to salts of the 3H-naphtho[1,2-d][1,2,3]dithiazolylium cation and its three selenium-containing variants
(SSeN, SeSN, and SeSeN) are described. The most efficient and general method involves the intermediacy of
bis-acetylated aminothiolates and aminoselenolates. These reagents react smoothly with sulfur and selenium halides
to afford the desired ring closure products. Electrochemical reduction of the four cations indicates that corresponding
radicals (SSN, SSeN, SeSN, and SeSeN) are stable in solution. The EPR spectra of all four have been recorded,
and experimental spin distributions have been cross-matched with those obtained from DFT calculations. The
selenium-containing radicals are thermally unstable at or slightly above room temperature, but the all-sulfur species
has been isolated and characterized crystallographically. In the solid state, the radicals are associated into cofacial
dimers which are closely linked to other dimers by intermolecular S---S, S---N, and C−H---aromatic ring interactions.