*Tetramethyl&shy;phosphonium fluoride  (CH)PF forms stable acetonitrile solutions. It is prepared from the ylide and potassium bifluoride:
:(CH)P=CH  +  KHF   →   (CH)PF  +  KF
:Gaseous tetramethylphosphonium fluoride exists as the phosphorane but autoionizes in acetonitrile solution. A more elaborate phosphazenium salt ([(CH)N)P]NF) is also known.
*Anhydrous Tetrabutylammonium fluoride has been prepared by the reaction of hexafluorobenzene and tetrabutylammonium cyanide.