Potassium hexafluorophosphate

Potassium hexafluorophosphate is the chemical compound with the formula KPF₆. This colourless salt consists of potassium cations and hexafluorophosphate anions. It is prepared by the reaction: ^[1]

PCl₅ + KCl + 6 HF → KPF₆ + 6 HCl

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This exothermic reaction is conducted in liquid hydrogen fluoride. The salt is stable in hot alkaline aqueous solution, from which it can be recrystallized. The sodium and ammonium salts are more soluble in water whereas the rubidium and caesium salts are less so.

KPF₆ is a common laboratory source of the hexafluorophosphate anion, used to confer lipophilicity to certain salts.

References

1. ^ Woyski, M. M. “Hexafluorophosphates of Sodium, Ammonium, and Potassium” Inorganic Syntheses volume III, pp. 111-117.