21501-81-5

Basic information

• Product Name: Oxonium hexafluoroarsenate(V)
• Synonyms: Oxonium hexafluoroarsenate(V)
• CAS NO: 21501-81-5
• Molecular Formula: AsF₆*H₃O
• Molecular Weight: 0
• Mol File: 21501-81-5.mol
• Article Data: 5

Chemical Properties

• Appearance: /
• CAS DataBase Reference: Oxonium hexafluoroarsenate(V)(CAS DataBase Reference)
• NIST Chemistry Reference: Oxonium hexafluoroarsenate(V)(21501-81-5)
• EPA Substance Registry System: Oxonium hexafluoroarsenate(V)(21501-81-5)

Safety Data

• Hazardous Substances Data: 21501-81-5(Hazardous Substances Data)

Upstream product

• 7784-36-3 arsenic pentafluoride 
• 7664-39-3 hydrogen fluoride 
• 7732-18-5 water 
• 14797-71-8 ¹⁸O-labeled water 
• 13968-48-4 ¹⁷O-water 
• 42246-22-0 technetium(VII) trioxyfluoride ⁽¹⁷⁾O-enriched 
• 7784-36-3 arsenic pentafluoride 
• 802971-81-9 [NH₃Cl]⁽¹⁺⁾*AsF₆^(1-)=[NH₃Cl]AsF₆ 

Downstream Products

• 223246-95-5 FOOBr 
• 21308-45-2 xenon difluoride * AsF₅ 
• 7664-39-3 hydrogen fluoride 
• 7784-36-3 arsenic pentafluoride 

Relevant articles and documents

Chemical synthesis of ozone, isotopic labeling, and redistribution

Ozone is formed in good yield by reacting O2/+ salts with water in HF at -78 °C. With isotopically labeled water 17O-16O-16O and 18O- 16O-16O can be prepared, and other isotopomers could be made by starting with 17O2/+ and 18O2/+ precursors. 17O NMR spectroscopy and IR matrix spectroscopy are used for detection and decay of the isotopomers. The 17O or 18O label at the terminal position remains at -78 °C, but at higher temperatures scrambling of the atoms is observed. Under strict monomolecular conditions no scrambling is observed till 450 °C, however. Irradiation of ozone in a 15K argon matrix with λ = 254 nm affords scrambling of the label and formation of oxygen. Irradiation with λ > 420 nm initiates only scrambling with little decay. The possible mechanisms of the atomic scrambling are discussed.

The [NH3Cl]+ ion

Stable! The first stable salts containing a simple, inorganic cation with an N-Cl bond are prepared (see picture). They are [NH3Cl] +[BF4]-, [NH3Cl] +[AsF6]-, and [NH3Cl] +[SbF6]- and can be safely prepared from (Me3Si)2NCl in mixtures of HF and the corresponding Lewis acids and could be used as storable generators for monochloramine gas.

Novel onium salts. Synthesis and characterization of OH3+SbF6- and OH3+AsF6-

The novel oxonium salts OH3+SbF6- and OH3+AsF6- were isolated as well-defined crystalline solids from the H2O-HF-SbF5 and the H2O-HF-AsF5 system, respectively. These salts are the most stable oxonium salts presently known. It was shown by DSC studies that OH3+SbF6- and OH3+AsF6- decompose at about 357 and 193°, respectively. Their ionic nature in both the solid state and polar solvents was established by vibrational and 19F and 1H NMR spectroscopy. The infrared spectra of these adducts closely resemble those recently attributed to H2F+ salts, suggesting that the latter may have been incorrectly identified. Furthermore, the frequencies of the OH3+ fundamentals in these salts are very similar to those of isoelectronic NH3, but significantly different from those previously observed for OH3+ in mineral acid monohydrates. This indicates that in the MF6- salts the hydrogen bridges are considerably weaker, although similar phenomena are observed for the low-temperature spectra suggesting rigidity of the lattice at low temperature. The assignments for OH3+ were examined by force field computations. On the basis of its X-ray powder diffraction pattern, OH3+AsF6- is cubic with a = 8.015 A?, Z = 4. From the H2O-HF-BF3 system a solid adduct was isolated at low temperature but was not further characterized owing to its thermal instability. A new method for drying HF based on oxonium salts is proposed.