The hexafluoroarsenate (sometimes shortened to fluoroarsenate) anion is a
chemical species with formula AsF−6. Hexafluoroarsenate is relatively inert, being the
conjugate base of the notional
superacidhexafluoroarsenic acid (HAsF6).
In the following reaction, one mole of arsenic trifluoride, three moles of silver fluoride, and one mole of nitrosyl chloride are reacted to produce one mole of nitrosyl hexafluoroarsenate, one mole of silver chloride, and two moles of elemental silver.
Like its pnictogen congeners, hexafluoroarsenate is a
noncoordinating anion, a
counterion used to stably store extremely reactive
cations.[5] Through the appropriate choice of fluorine donor, the synthesis of hexafluoroarsenate can also double as preparation of an exotic cation.[2][6] The resulting salts are typically stable to
metathesis with
silver(I),
ammonium,
potassium, or
caesium ions.[3][2] Unlike the former three, caesium hexafluoroarsenate is
insoluble in water.
Intercalation compounds of
graphite and hexafluoroarsenic acid exhibit unusually high conductivity, leading to early proposals that the acid might serve as an
electrode or
electrolyte in high-energy batteries.[9][4] Subsequent investigation revealed that the high conductivity occurs because both
electron holes in the graphite and the hexafluoroarsenate ions themselves serve as
charge carriers.[9][10]
Dess 1955 cites Marignac, M. C. (1867). "Sur Quelques Fluosels de l'Antimoine et de l'Arsenic" [On Some Fluorine Salts of Antimony and Arsenic]. Annales de chimie et de physique (in French): 371–385 – via Gallica, but discounts it as describing an implausibly easy synthesis with a hydrolyzable product.
^
abLawless, Edward W.; Wiegand, C. J. Wesley; Mizumoto, Yukio; Weis, Constance (July 28, 1970). "Lithium Hexafluoroarsenate and Hexafluoroarsenic Acid". Inorganic Chemistry. 10 (5) (published 1971): 1084–1086.
doi:
10.1021/ic50099a048.
^Maia Melo, Sérgio; Sousa Silveira, Alexandre (3 February 1983). "Hexafluoroarsenate as a Non-Coordinating Anion in Lanthanide Complexes with the Diphenyl Sulphoxide Ligand". Journal of the Less Common Metals. 94 (2). The Netherlands: Elsevier Sequoia: 305–308.
doi:
10.1016/0022-5088(83)90029-2.
^Desmarteau, Darryl D.; Lam, William Y.; O'Brien, Brian A.; Shi-Ching Chang (December 5, 1983). "Novel Ammonium Hexafluoroarsenate Salts from Reaction of (CF3)2NH, CF3N(OCF3)H, CF3N[OCF(CF3)2]H, CF3NHF and SF5NHF with the Strong Acid HF/AsF5". Journal of Fluorine Chemistry. 25 (3). The Netherlands: Elsevier Sequoia S.A. (published 1984): 387–394.
doi:
10.1016/S0022-1139(00)81212-9.
^Axhausen, Joachim; Lux, Karin; Kornath, Andreas (2014). "The Existence of Hexafluoroarsenic(V) Acid". Angewandte Chemie International Edition. 53 (14). Wiley: 3720–3721.
doi:
10.1002/anie.201308023.
PMID24446235.
^Davidson, D. W.; Calvert, L. D.; Lee, F.; Ripmeester, J. A. (31 July 1980). "Hydrogen Fluoride Containing Isostructural Hydrates of Hexafluorophosphoric, Hexafluoroarsenic, and Hexafluoroantimonic Acids". Inorg. Chem. 20 (published 1981): 2013–2016.
doi:
10.1021/ic50221a016. Also published as
NRCC 18823.
^
abVogel, F. L.; Foley, G. M. T.; Zeller, C.; Falardeau, E. R.; Gan, J. (1977). "High Electrical Conductivity in Graphite Intercalated with Acid Fluorides". Materials Science and Engineering. 31. The Netherlands/Lausanne, Switzerland: Elsevier Sequoia S.A.: 261–265.
doi:
10.1016/0025-5416(77)90043-X.
^Milliken, J. W.; Fischer, J. E. (1 May 1983). "Ionic Salt Limit in Graphite–Fluoroarsenate Intercalation Compounds". J. Chem. Phys. 78 (9) (published 31 August 1998): 5800–5808.
Bibcode:
1983JChPh..78.5800M.
doi:
10.1063/1.445423.