Hexafluorophosphoric acid

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]

Hexafluorophosphoric acid^[1]

Names
IUPAC name Hexafluorophosphoric acid[2]
Other names Hydrogen hexafluorophosphate Hydron hexafluorophosphate
Identifiers
CAS Number	16940-81-1 Y
3D model (JSmol)	Interactive image
ChemSpider	17339451 N
ECHA InfoCard	100.037.263
EC Number	241-006-5
PubChem CID	16211447
CompTox Dashboard (EPA)	DTXSID40884947
InChI InChI=1S/F6P/c1-7(2,3,4,5)6/q-1/p+1 N Key: LJQLCJWAZJINEB-UHFFFAOYSA-O N InChI=1/F6P/c1-7(2,3,4,5)6/q-1/p+1 Key: LJQLCJWAZJINEB-IKLDFBCSAL
SMILES [H+].F[P-](F)(F)(F)(F)F
Properties
Chemical formula	HPF6
Molar mass	145.972 g/mol
Appearance	colorless oily liquid
Melting point	decomposes at 25 °C
Solubility in water	exists only in solution
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Corrosive
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H311, H314, H330
Precautionary statements	P260, P264, P271, P280, P284, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P320, P321, P363, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

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

See also

• Fluoroantimonic acid

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. 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.