Bis(perfluoroorganyl)bromonium salts [(RF)2Br]Y (RF = aryl, alkenyl, and alkynyl)

Bromonium salts (R_F)₂Br]Y with perfluorinated groups R_FC₆F₅, CF₃CFCF, C₂F₅CFCF, and CF₃C≡C were isolated from reactions of BrF₃ with R_FBF₂ in weakly coordinating solvents (wcs) like CF₃CH₂CHF₂ (PFP) or CF₃CH₂CF₂CH₃ (PFB) in 30-90% yields. C₆F₅BF₂ formed independent of the stoichiometry only (C₆F₅)₂Br]BF₄]. 1:2 reactions of BrF₃ and silanes C₆F₅SiY₃ (Y = F, Me) ended with different products - C₆F₅BrF₂ or (C₆F₅)₂Br]SiF₅] - as pure individuals, depending on Y and on the reaction temperature (Y = F). With C₆F₅SiF₃ at ≥−30 °C (C₆F₅)₂Br]SiF₅] resulted in 92% yield whereas the reaction with less Lewis acidic C₆F₅SiMe₃ only led to C₆F₅BrF₂ (58%). The interaction of KC₆F₅BF₃] with BrF₃ or BrF₂]SbF₆] in anhydrous HF gave (C₆F₅)₂Br]SbF₆]. Attempts to obtain a bis(perfluoroalkyl)bromonium salt by reactions of C₆F₁₃BF₂ with BrF₃ or of KC₆F₁₃BF₃] with BrF₂]SbF₆] failed. The 3:2 reactions of BrF₃ with (C₆F₅)₃B in CH₂Cl₂ gave (C₆F₅)₂Br](C₆F₅)_nBF_4−n] salts (n = 0-3). The mixture of anions could be converted to pure BF₄]⁻ salts by treatment with BF₃·base.