Replacement of Trimethylamine in Trimethylamine‐trispentafluoroethyl‐borane. Structures of [(C 2 F 5 ) 3 BNMe 3 ], [NMe 4 ][(C 2 F 5 ) 3 BOH], and K[(C 2 F 5 ) 3 BCH 2 (CO)C 6 H 5 ]

Trimethylamine‐tris(pentafluoroethyl)borane [(C 2 F 5 ) 3 BNMe 3 ] ( 1 ) reacts at 190 °C with water under displacement of the trimethylamine ligand to yield the hydroxy‐tris(pentafluoroethyl)borate [(C 2 F 5 ) 3 BOH] − ( 2 ). In tributylamine 1 reacts with alkynes HC≡CR to form novel ethynyl‐tris(pentafluoroethyl)borate anions [(C 2 F 5 ) 3 BC≡CR] − – R = C 6 H 5 ( 3 ), C 6 H 4 CH 3 ( 4 ), Si(CH(CH 3 ) 2 ) 3 ( 5 ) – in moderate yields. Compound 3 adds water across the triple bond to form the novel anion [(C 2 F 5 ) 3 BCH 2 (CO)C 6 H 5 ] − ( 6 ). The structures of [(C 2 F 5 ) 3 BNMe 3 ], [NMe 4 ][(C 2 F 5 ) 3 BOH] and K[(C 2 F 5 ) 3 BCH 2 (CO)C 6 H 5 ] have been determined by x‐ray crystallography.