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Arsenic trifluoride
Names
	IUPAC name Arsenic(III) fluoride
	Other names Arsenic trifluoride, trifluoroarsane, TL-156
Identifiers
CAS Number	7784-35-2 ;
3D model (JSmol)	Interactive image;
ChemSpider	22975 ;
ECHA InfoCard	100.029.145
EC Number	232-060-0;
PubChem CID	24571;
RTECS number	CG5775000;
UNII	R4I21S44T9;
CompTox Dashboard (EPA)	DTXSID9064841 ;
	InChI InChI=1S/AsF3/c2-1(3)4 Key: JCMGUODNZMETBM-UHFFFAOYSA-N ; InChI=1/AsF3/c2-1(3)4 Key: JCMGUODNZMETBM-UHFFFAOYAJ;
	SMILES F[As](F)F;
Properties
Chemical formula	AsF3
Molar mass	131.9168 g/mol
Appearance	colorless oily liquid
Density	2.666 g/cm3 (0 °C)
Melting point	−8.5 °C (16.7 °F; 264.6 K)
Boiling point	60.4 °C (140.7 °F; 333.5 K)
Solubility in water	decomposes
Solubility	soluble in alcohol, ether, benzene and ammonia solution
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Toxic, corrosive
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H311, H331
Precautionary statements	P261, P264, P270, P271, P280, P301+P310, P302+P352, P304+P340, P311, P312, P321, P322, P330, P361, P363, P403+P233, P405, P501
	NIOSH (US health exposure limits):
PEL (Permissible)	[1910.1018] TWA 0.010 mg/m3
REL (Recommended)	Ca C 0.002 mg/m3 [15-minute]
IDLH (Immediate danger)	Ca [5 mg/m3 (as As)]
Thermochemistry
Std enthalpy of; formation (ΔfH⦵298)	-821.3 kJ/mol
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) 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] Like other inorganic arsenic compounds, it is highly toxic.

Preparation and properties

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 a fluorinating agent for the conversion of 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]

AsF₃ reacts with SbF₅. The product obtained could be described as the ionic compound AsF₂⁺ SbF₆⁻. However, the authors conclude the formed product cannot be viewed only as an ionic compound nor entirely as the neutral adduct AsF₃SbF₅. The crystal structure displays characteristics of both an ionic pair, and a neutral adduct, taking the middle ground in between both models. ^[7]

References

^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
^ ^a ^b ^c NIOSH Pocket Guide to Chemical Hazards. "#0038". National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b ^c ^d Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
^ New alkali metal and tetramethylammonium tetrafluoroarsenates(III), their vibrational spectra and crystal structure of caesium 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
^ 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
^ 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