Ya. Veits et al., Aromatic nucleophilic substitution in pentafluoropyridine by three-coordinate phosphorus compounds, RUSS J ORG, 36(5), 2000, pp. 750-756
Pentafluoropyridine reacts with primary, secondary, and tertiary phosphines
or their trimethylsilyl analogs under mild conditions without a catalyst t
o afford new pi -acceptor organophosphorus ligands containing one, two, or
three tetrafluoropyridyl groups on the phosphorus atom.