The oxychloride, bromides, and other compounds were subsequently discovered; here we need only notice Moissan's preparation of the trifluoride and Thorpe's discovery of the pentafluoride, a compound of especial note, for it volatilizes unchanged, giving a vapour of normal density and so demonstrating the stability of a pentavalent phosphorus compound (the pentachloride and pentabromide dissociate into a molecule of the halogen element and phosphorus trichoride).
Columbium pentafluoride, CbF5, is obtained when the pentoxide is dissolved in hydrofluoric acid.
Tantalum pentafluoride, TaF5, for a long time only known in solution, may be obtained by passing fluorine over an alloy of tantalum and aluminium, and purifying by distillation in a vacuum.
Electric sparks give at first free sulphur and the trifluoride, the latter at a higher temperature splitting into the pentafluoride and phosphorus.
