Hydrogen fluoride solvent system. Part III. Solutions of the acids SbF 5 , AsF 5 , and PF 5 . Evidence for the As 2 F 11 – ion

Cryoscopic measurements on solutions of antimony pentafluoride in HF confirm that it is a strong 1 : 1 electrolyte in dilute solutions. Cryoscopic and conductimetric measurements show that arsenic pentafluoride dissolves to form the strong electrolyte H2F+As2F11–. The dimeric anion As2F11– has been isolated as the tetraethylammonium salt. Phosphorus pentafluoride appears to be a non-electrolyte in this solvent.