SYNTHESES AND REACTIONS OF FLUOROORGANIC ACYCLIC THIOCARBENIUM IONS

Arsenic pentafluoride oxidizes (F3CS)4C (1) but not (F3CS)2C=C(SCF3)2 (2) to yield the stable salt (F3CS)3C+ AsF6- (3). It reacts with halide ions to form (F3CS)3CX (3a-c, X = F, Cl, Br). Iodide is oxidized to iodine with formation of (F3CS)3CC(SCF3)3 (4) which reacts with nitrogen dioxide to give (F3CS)3CNO2 (3e). - (F3CS)3C+AsF6- (3) removes from S-CF2-S-C(F)-SCF3 (5a) a ring-bound fluorine atom to afford (F3CS)3CF and [S-CF2-S-C-SCF3]+AsF6- (5). When (F3CS)3CCl (3b) is treated with AsF5, 3 and [(F3CS)2-CCl]+AsF6- (6) are formed in a 2:1 molar ratio. The latter reacts with F- or Cl- to give (F3CS)2CClX (6a,b; X = F, CI). AsF5 is capable of abstracting a fluoride ion from (F3CS)3-n Cl(n)CF only if n = 0 or 1. For n = 2 no similar reaction takes place, but with AlCl3 in BCl3 halogen exchange to F3CSCCl3 (7b) is observed. - Alkylation of (F3CS)2C=S (8) with H3CF/AsF5 yields [(F3CS)2CSCH3]+AsF6- (9), which adds a fluoride ion to give (F3CS)2(H3CS)CF (9a). The molecular structures of (F3CS)2C=C(SCF3)2 (2) and (F3CS)3CC(SCF3)3 (4) have been determined by X-ray diffraction methods.