What is "hexafluorophosphoric acid"

n. (context inorganic compound English) The chemical compound HPF₆, a strong Brønsted acid.

Hexafluorophosphoric acid is the inorganic compound with the chemical formula HOPF. Although the formula is often written as HPF, this compound is only available as the hydrate. This strong Brønsted acid features a non-coordinating anion, hexafluorophosphate . It is formed from the reaction of hydrogen fluoride with phosphorus pentafluoride.

Like many strong acids, hexafluorophosphoric acid is not isolable but is handled only in solution. Its aqueous solutions consist of hydronium ion, , and . Additionally, such solutions often contain products derived from hydrolysis of the P-F bonds, including , , and , and their conjugate bases. Hexafluorophosphoric acid attacks glass. Upon heating, it decomposes to generate HF. Crystalline has been obtained as the hexahydrate, wherein is enclosed in truncated octahedral cages defined by the water and protons. NMR spectroscopy indicates that solutions derived from this hexahydrate contain significant amounts of HF.