Syntheses of Cyclic and Acyclic Bis(perfluoroalkylthio)nitronium Salts

Abstract(F3CS)3N (1) is oxidized quantitatively by AsF5 to the first bis(perfluoroalkylthio)nitronium salt (F3CS)2N+AsF−6 (2). Addition of halide ions (F−, Cl−, Br−, l−) to the cation of 2 destroys the SNS chain. (F2CSCl)2 undergoes with ammonia a cyclization reaction to SCF2CF2SNH (3), which can be derivatized with F3CSCl or (F2CSCl)2 to SCF2CF2SNSCF3 (3a) and (SCF2CF2SNSCF2)2 (3b), respectively. Oxidation of 3a with AsF5 yields (SCF2CF2SN+AsF−6 (4) and byproducts, which suggest formation of a {3a}+• radical cation as an intermediate in this reaction. Pure 4 is accessible by reaction of 3 with AsF5 in 54% yield. The chemical and spectroscopic properties of the new species are discussed.