Arsenic trifluoride

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Arsenic trifluoride
IUPAC name
Arsenic(III) fluoride
Other names
Arsenic trifluoride, trifluoroarsane
3D model (Jmol) Interactive image
ChemSpider 22975
ECHA InfoCard 100.029.145
PubChem 24571
RTECS number CG5775000
Molar mass 131.9168 g/mol
Appearance colorless liquid
Density 2.666 g/cm3[1]
Melting point −8.5 °C (16.7 °F; 264.6 K)
Boiling point 60.4 °C (140.7 °F; 333.5 K)
Solubility soluble in alcohol, ether, benzene and ammonia solution
Main hazards Toxic, corrosive
R-phrases R23/25, R50/53
S-phrases (S1/2), S20/21, S28, S45, S60, S61
US health exposure limits (NIOSH):
PEL (Permissible)
[1910.1018] TWA 0.010 mg/m3[2]
REL (Recommended)
Ca C 0.002 mg/m3 [15-minute][2]
IDLH (Immediate danger)
Ca [5 mg/m3 (as As)][2]
-821.3 kJ/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Arsenic trifluoride is a chemical compound of arsenic and fluorine with the chemical formula AsF3. It is a colorless liquid which reacts readily with water.[3]

Preparation and properties[edit]

It can be prepared by reacting hydrogen fluoride, HF, with arsenic trioxide:[3]

6HF + As2O3 → 2AsF3 + 3H2O

It has a pyramidal molecular structure in the gas phase which is also present in the solid.[3] In the gas phase the As-F bond length is 170.6 pm and the F-As-F bond angle 96.2°.[4]

Arsenic trifluoride is used as fluorinating non-metal chlorides to fluorides, in this respect it is less reactive than SbF3.[3]

Salts containing AsF4 anion can be prepared for example CsAsF4.[5] the potassium salt KAs2F7 prepared from KF and AsF3 contains AsF4 and AsF3 molecules with evidence of interaction between the AsF3 molecule and the anion.[6]

With SbF5 the ionic adduct AsF2+ SbF6 is produced [7]


  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  2. ^ a b c "NIOSH Pocket Guide to Chemical Hazards #0038". National Institute for Occupational Safety and Health (NIOSH). 
  3. ^ a b c d Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9. 
  4. ^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
  5. ^ New alkali metal and tetramethylammonium tetrafluoroarsenates(III), their vibrational spectra and crystal structure of cesium tetrafluoroarsenate(III)Klampfer P, Benkič P, Lesar A, Volavšek B, Ponikvar M , Jesih A., Collect. Czech. Chem. Commun. 2004, 69, 339-350 doi:10.1135/cccc20040339
  6. ^ Alkali-metal heptafluorodiarsenates(III): their preparation and the crystal structure of the potassium salt, Edwards A.J., Patel S.N., J. Chem. Soc., Dalton Trans., 1980, 1630-1632, doi:10.1039/DT9800001630
  7. ^ Fluoride crystal structures. Part XV. Arsenic trifluoride–antimony pentafluoride, Edwards A. J., Sills R. J. C. J. Chem. Soc. A, 1971, 942 - 945, doi:10.1039/J19710000942