Improved Access to Organo-Soluble Di- and Tetrafluoridochlorate(I)/(III) Salts

A facile one-pot gram-scale synthesis of tetraalkylammonium tetrafluoridochlorate(III) [cat][ClF₄ ] ([cat]=[NEt₃ Me]⁺ , [NEt₄ ]⁺ ) is described. An acetonitrile solution of the corresponding alkylammonium chloride salt is fluorinated with diluted fluorine at low temperatures. The reaction proceeds via the [ClF₂ ]^- anion which is structurally characterized for the first time. The potential application of [ClF₄ ]^- salts as fluorinating agents is evaluated by the reaction with diphenyl disulfide, Ph₂ S₂ , to pentafluorosulfanyl benzene, PhSF₅ . The CN moieties in acetonitrile and [B(CN)₄ ]^- are transferred in CF₃ groups. Exposure of carbon monoxide, CO, leads to the formation of carbonyl fluoride, COF₂ , and elemental gold is dissolved under the formation of tetrafluoridoaurate [AuF₄ ]^- .