Hexafluorophosphoric acid refers to a family of salts produced by combining phosphorus pentafluoride and hydrofluoric acid. The idealized chemical formula for hexafluorophosphoric acid is HPF6, which also is written H[PF]6.[3] Hexafluorophosphoric acid is only stable in solution, decomposing to HF and PF5 when dry.[4] It exothermically reacts with water to produce oxonium hexafluorophosphate (H3OPF6) and hydrofluoric acid. Additionally, such solutions often contain products derived from hydrolysis of the P-F bonds, including HPO
2F
2, H
2PO
2F, and H
3PO
4, and their conjugate bases.[5] Hexafluorophosphoric acid attacks glass. Upon heating, it decomposes to generate HF. Crystalline HPF
6 has been obtained as the hexahydrate, wherein PF−
6 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.[5]

Whereas a species with the formula HPF6 remains unknown, the analogous molecular hexafluoroarsenic acid (HAsF6) has been crystallized.[6]

See also

References

  1. ^ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 4–74. ISBN 0-8493-0594-2.
  2. ^ IUPAC. "Nomenclature of Inorganic Chemistry". Retrieved 2021-04-08.
  3. ^ Arpad Molnar; G. K. Surya Prakash; Jean Sommer (2009). Superacid Chemistry (2nd ed.). Wiley-Interscience. p. 44. ISBN 978-0-471-59668-4.
  4. ^ Lindahl, Charles B.; Mahmood, Tariq (2000), "Fluorine compounds, inorganic, phosphorus", Kirk-Othmer Encyclopedia of Chemical Technology, New York: John Wiley, doi:10.1002/0471238961.1608151912091404.a01, ISBN 9780471238966
  5. ^ a b D. W. Davidson; S. K. Garg (May 1972). "The Hydrate of Hexafluorophosphoric Acid". Canadian Journal of Chemistry. 50 (21): 3515–3520. doi:10.1139/v72-565.
  6. ^ Axhausen, Joachim; Lux, Karin; Kornath, Andreas (2014). "The Existence of Hexafluoroarsenic(V) Acid". Angewandte Chemie International Edition. 53 (14): 3720–3721. doi:10.1002/anie.201308023. PMID 24446235.