Arsenic(III) Fluoride1


[7784-35-2]  · AsF3  · Arsenic(III) Fluoride  · (MW 131.92)

(arsenating agent;2 fluorinating agent3)

Alternate Name: arsenic trifluoride.

Physical Data: mp -5.95 °C (-8.5 °C); bp 57.8 °C (63 °C); d15 2.73 g cm-3.

Solubility: sol ether, THF, C6H6, hydrocarbons, alcohols; hydrolyzes in H2O.

Form Supplied in: colorless, mobile liquid; commercially available.

Analysis of Reagent Purity: 19F NMR, Raman spectrum.4

Preparative Methods: several methods exist for the preparation of arsenic trifluoride.5

Purification: the reagent can be purified by distillation at atmospheric pressure in an all-glass or iron system.5

Handling, Storage, and Precautions: when heated, AsF3 decomposes to highly toxic fumes containing As0.6 Additionally, it will fume in air and is readily hydrolyzed. Contact with skin results in burns similar to those caused by HF.5a Since AsF3 reacts with glass over time, it should be stored in polyethylene or iron containers.5 This reagent should be handled in a fume hood.

Use as an Arsenating Agent.

Arsenic trifluoride has seen its most extensive use in organic chemistry as an arsenating agent. Usually, the fluoride ligands are exchanged with another ligand such as an amine (eq 1).7 Cyclic arsenic compounds can be synthesized in moderate to good yields by using bidentate ligands (eq 2).2a,8

Some advantage has been taken of the strength of the silicon-fluorine bond in these exchange reactions (eqs 3 and 4).2b,9 Not surprisingly, the product cyclopentadienylarsenic difluoride (eq 4) is unstable and polymerizes upon distillation at 30 °C.9

There is some indication that AsF3 is less reactive with organic compounds than AsCl3 and the higher homologs (eq 5).2c,10 Usefully, organoarsenic mono-11 and difluorides2c can be converted to the arsenic hydrides by reaction with Lithium Aluminum Hydride (eq 6).11

Importantly, AsF3 can be added across alkenes in the presence of Antimony(V) Fluoride (eqs 7 and 8).12,13 Although stoichiometrically the AsF3 seems to simply add to the alkene, it is more likely that the reactive species is AsF2+SbF-6 in these transformations.12

Use as a Fluorinating Agent.

Although milder than SbF3, AsF3 can also be used as fluorinating agent. Typically, a ligand exchange reaction occurs in which the fluoride ligands are exchanged for other ligands such as another halide (eq 9).3,14

Fluck et al. have used AsF3 in several exchange reactions with Et2N ligands on trivalent phosphorus to generate phosphorus-fluorine bonds (eqs 10 and 11).15,16

1. (a) Kemmitt, R. D. W.; Sharp, D. W. A. Adv. Fluorine Chem. 1965, 4, 208. (b) The Merck Index, 11th ed.; Budavaris, S., Ed.; Merck: New Jersey, 1989; p 837. (c) Dictionary of Inorganic Compounds; Macintyre, J. E., Ed.; Chapman & Hall: New York, 1992; Vol. 1, p 84.
2. (a) Kober, F.; Rühl, W. J. JOM 1975, 101, 57. (b) Janzen, A. F.; Vaidya, O. C.; Willis, C. J. J. Inorg. Nucl. Chem. 1981, 43, 1469. (c) Cowley, A. H.; Kilduff, J. E.; Lasch, J. G.; Mehrotra, S. K.; Norman, N. C.; Pakulski, M.; Whittlesey, B. R.; Atwood, J. L.; Hunter, W. E. IC 1984, 23, 2582.
3. (a) Jutzi, P.; Seufert, A. JOM 1979, 169, 357. (b) Roesky, H. W.; Sotoodeh, M.; Xu, Y. M.; Schrumpf, F.; Noltemeyer, M. Z. Anorg. Allg. Chem. 1990, 580, 131.
4. For the 19F NMR, see Kadaba, P. K. Mol. Phys. 1975, 29, 1485. For the Raman spectrum, see Yost, D. M.; Sherborne, J. E. JACS 1935, 57, 700.
5. (a) Hoffman, C. J. Inorganic Synthesis; McGraw-Hill: New York, 1953; vol. 4, p 150 and references cited therein. (b) Kwasnik, W. Handbook of Preparative Inorganic Chemistry, 2nd ed.; Brauer, G., Ed.; Academic Press: New York, 1963; Vol. 1, p. 197.
6. Dangerous Properties of Industrial Materials, 6th ed.; Sax, N. I., Ed.; Van Nostrand Reinhold: New York, 1984; p. 322.
7. Olah, G. A.; Oswald, A. A. CJC 1960, 38, 1431.
8. Kober, F.; Rühl. W. J. Z. Anorg. Allg. Chem. 1975, 416, 57.
9. Jutzi, P.; Kuhn, M. CB 1974, 107, 1228.
10. Cowley, A. H.; Lasch, J. G.; Norman, N. C.; Pakulski, M. JACS 1983, 105, 5506.
11. Scholz, M; Roesky, H. W.; Stalke, D.; Keller, K.; Edelmann, F. T. JOM 1989, 366, 73.
12. Tittle, B. JFC 1973, 2, 449.
13. (a) Kopaevich, Y. L.; Belen'kii, G. G.; Mysov, E. I.; German, L. S.; Knunyants, I. L. IZV 1973, 22, 121. (b) Kopaevich, Y. L.; Belen'kii, G. G.; German, L. S. IZV 1973, 22, 646.
14. (a) Ruf, W.; Renk, T.; Siebert, W. ZN(B) 1976, 31, 1028. (b) Renk, T.; Ruf, W.; Siebert, W. JOM 1976, 120, 1.
15. Svara, J.; Fluck, E.; Stezowski, J. J.; Maier, A. Z. Anorg. Allg. Chem. 1987, 545, 47.
16. Fluck, E.; Kuhm, P. PS 1989, 42, 123.

Scott D. Edmondson

The Ohio State University, Columbus, OH, USA

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