Synthesis of a Perfluorinated Phenoxyphosphorane and Conversion to Its Hexacoordinate Anions

We report the synthesis and structural characterization of a neutral PV Lewis acid, P(OC6F5)5, and salts containing the six‐coordinate anions [P(OC6F5)5F]− and [P(OC6F5)6]−. The latter anion exhibits a rare example of F–πarene interactions in both the solid and the solution phase, which has been quantitatively studied by variable‐temperature (VT) NMR spectroscopy. The Lewis acid strength of P(OC6F5)5 has been assessed through experimental fluoride ion competition experiments and quantum‐chemical calculations of its fluoride ion affinity (FIA) and global electrophilicity index (GEI). Our findings highlight the importance of considering solvent effects in electrophilicity calculations, even when neutral Lewis acids are involved, and show a rare divergence between FIA and GEI trends. The coordinating abilities of the [P(OC6F5)6]− and [P(OC6F5)5F]− anions towards the trityl cation, as a prototypical electrophile, have been assessed. Lewis acidic, but labile: We report the synthesis and structures of the homoleptic phosphorane P(OC6F5)5 as well as the anions [P(OC6F5)5F]− and [P(OC6F5)6]−. The anions show rare examples of F–πarene interactions (see graphic), which have been quantified. The Lewis acidity of the neutral species and the stabilities of the anions have been assessed.