Arsenic trifluoride is a
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
of
arsenic
Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, ...
and
fluorine with the chemical formula AsF
3. It is a colorless liquid which reacts readily with water.
Preparation and properties
It can be prepared by reacting
hydrogen fluoride, HF, with
arsenic trioxide
Arsenic trioxide, sold under the brand name Trisenox among others, is an inorganic compound and medication. As an industrial chemical, whose major uses include in the manufacture of wood preservatives, pesticides, and glass. As a medication, it ...
:
:6HF + As
2O
3 → 2AsF
3 + 3H
2O
It has a pyramidal molecular structure in the gas phase which is also present in the solid.
In the gas phase the As-F bond length is 170.6 pm and the F-As-F bond angle 96.2°.
Arsenic trifluoride is used as a fluorinating agent for the conversion of non-metal chlorides to fluorides, in this respect it is less reactive than SbF
3.
Salts containing AsF
4− anion can be prepared for example CsAsF
4. the potassium salt KAs
2F
7 prepared from KF and AsF
3 contains AsF
4− and AsF
3 molecules with evidence of interaction between the AsF
3 molecule and the anion.
AsF
3 reacts with
SbF5. The product obtained could be described as the ionic compound AsF
2+ SbF
6−. However, the authors conclude the formed product cannot be viewed only as an ionic compound nor entirely as the neutral adduct AsF
3SbF
5. The crystal structure displays characteristics of both an ionic pair, and a neutral adduct, taking the middle ground in between both models.
[Fluoride crystal structures. Part XV. Arsenic trifluoride–antimony pentafluoride, Edwards A. J., Sills R. J. C. J. Chem. Soc. A, 1971, 942 - 945, ]
References
{{DEFAULTSORT:Arsenic Trifluoride
Arsenic(III) compounds
Arsenic halides
Fluorides
Fluorinating agents