Arsenic trifluoride

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Arsenic trifluoride
IUPAC name Arsenic(III) fluoride
Other names Arsenic trifluoride
Identifiers
CAS number [7784-35-2]
Properties
Molecular formula AsF3
Molar mass 131.91g mol-1
Appearance colorless liquid
Density 2.7 g cm-3[1]
Melting point

-6 ˚C[1]
Boiling point

58 ˚C[1]
Solubility in water N/A
Hazards
Main hazards Toxic, corrosive
R-phrases R23/25, R50/53
S-phrases (S1/2), S20/21, S28, S45, S60, S61
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Arsenic trifluoride is a chemical compound of arsenic and fluorine with the formula AsF3. It is a colorless liquid which reacts readily with water.[2]

[edit] Preparation and properties

It can be prepared by reacting hydrogen fluoride,HF, with arsenic trioxide:[2]

6HF + As2O3 → 2AsF3 + 3H2O

It has a pyramidal molecular structure in the gas phase which is also present in the solid.[2] Its enthalpy of formation is -305.0kJ/mol.
Arsenic trifluoride is used as fluorinating non-metal chlorides to fluorides, in this respect it is less reactive than SbF3.[2]
Salts containing AsF4− anion can be prepared for example Cs2AsF4 [3]. 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.[4]
With SbF5 the ionic adduct AsF2+ SbF6− is produced [5]

[edit] References

  1. ^ a b c Arsenic trifluoride at webelements.com
  2. ^ a b c d Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4. 
  3. ^ 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
  4. ^ 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
  5. ^ 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
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