Organoethynylxenon(II) Tetrafluoroborates, [RC≡CXe][BF 4 ] – The First Examples of Isolated Alkynylxenonium Salts: Preparation and Multi‐NMR Characterisation

The perfluorinated organoethynylxenon(II) salts, [RC≡CXe][BF 4 ] [R = CF 3 , C 3 F 7 , (CF 3 ) 2 CF, cis ‐, trans ‐CF 3 CF=CF, C 6 F 5 ], were prepared by the reaction of XeF 2 with the corresponding perfluoroorganoethynyldifluoroboranes, RC≡CBF 2 , in 1,1,1,3,3‐pentafluoropropane (PFP) or CH 2 Cl 2 at –60 to –40 °C and isolated in 30–98 % yield. Similarly, the non‐fluorinated organoethynylxenon(II) salts [C 4 H 9 C≡CXe][BF 4 ] and [(CH 3 ) 3 CC≡CXe][BF 4 ] were obtained in 20 to 40 % yield. All [RC≡CXe][BF 4 ] salts are soluble in anhydrous HF (aHF) and the salts with R = C 4 H 9 or R = (CH 3 ) 3 C display sufficient solubility in the weakly coordinating solvents CH 2 Cl 2 and PFP. The xenonium salts [RC≡CXe][BF 4 ] were unambiguously characterised by their 1 H‐, 11 B‐, 13 C‐, 19 F‐, and 129 Xe NMR spectra in solution. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)