Perfluoroorganylxenonium(II) salts from reactions of XeF2 or [FXe][SbF6] with selected perfluorinated alk-1-yn-1-yl- and alk-1-en-1-yltrifluoroborate salts in aHF

Xenon difluoride reacted with alkynylborate salts, K[RFCCBF3], in anhydrous HF (aHF) to give alkynylxenonium salts, [RFCCXe][BF4] (RF = CF3, C3F7, (CF3)2CF), in 50–55% yield. Both [FXe][SbF6] and K[C3F7CCBF3] formed the [C3F7CCXe]+ salt in aHF. In the reaction of XeF2 with the alkenylborate salt, K[CF2C(CF3)BF3], the competitive hydrodeboration reaction (formation of CF2C(CF3)H in 85% yield) exceeded the xenodeboration reaction (formation of the xenonium salt [CF2C(CF3)Xe][BF4] in 15% yield only). K[4-BF3C5F4N] did not react with XeF2 in aHF, but underwent fluorine addition in the presence of AsF5.

Perfluoroorganyltrifluoroborate salts do not react with XeF2 in halocarbons or CH3CN, but in aHF, HF activates XeF2 and enables electrophilic attack on the nucleophilic ipso-carbon of the CBF3 moiety. This “xenodeboration” approach is a new method for the synthesis of XeC onium salts.Figure optionsDownload as PowerPoint slideHighlights
► A new method of xenodeboration that allows the syntheses of perfluoroorganylxenonium tetrafluoroborate salts.
► Perfluorinated alkynyl-, alkenyl-, and arylxenonium salts are accessible by xenodeboration.
► AHF increases the electrophilicity of XeF2 which enables electrophilic attack of Xe(II) at the ipso-carbon of the CB bond.