Thionyl fluoride

Thionyl fluoride
IUPAC name
Thionyl fluoride
7783-42-8 N
3D model (Jmol) Interactive image
ChemSpider 22954 YesY
ECHA InfoCard 100.029.088
PubChem 24548
Molar mass 86.06 g·mol−1
Appearance colorless gas
Melting point −110.5 °C (−166.9 °F; 162.7 K)
Boiling point −43.8 °C (−46.8 °F; 229.3 K)
Solubility soluble in ethanol, ether, benzene
Vapor pressure 75.7 kPa (-50 °C)[1]
trigonal pyramidal
278.6 J/mol·K[2]
-715 kJ/mol[2]
56.8 J/mol·K[2]
R-phrases R36/37/38[3]
S-phrases S36/37, S38, S45, S63
Related compounds
Related oxohalides
Thionyl chloride
Thionyl bromide
Related compounds
Nitrosyl fluoride
Carbonyl fluoride
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

Thionyl fluoride is the inorganic compound with the formula SOF2. This colourless gas is mainly of theoretical interest, but it is a product of the degradation of sulfur hexafluoride, an insulator in electrical equipment. The molecule adopts a distorted pyramidal structure, with Cs symmetry. The S-O and S-F distances are 1.42 and 1.58 Å, respectively. The O-S-F and F-S-F angles are 106.2 and 92.2°, respectively. Thionyl chloride and thionyl bromide have similar structures, although these compounds are liquid at room temperature. Mixed halides are also known, such as SOClF, thionyl chloride fluoride.[4]

Synthesis and reactions

Thionyl fluoride can be produced by the reaction of thionyl chloride with fluoride sources such as antimony trifluoride.[5][6]

3 SOCl2 + 2SbF3 → 3SOF2 + 2SbCl3

Alternatively, it arises via the fluorination of sulfur dioxide:[6]

SO2 + 2PF5 → SOF2 + POF3

Thionyl fluoride arises as a fleeting intermediate from the decomposition of sulfur hexafluoride as the result of electrical discharges which generate sulfur tetrafluoride. SF4 hydrolyzes to give thionyl fluoride, which in turn hydrolyzes further as described below.[7]

As expected from the behavior of the other thionyl halides, this compound hydrolyzes readily, giving hydrogen fluoride and sulfur dioxide:[6]

SOF2 + H2O → 2HF + SO2

In contrast to thionyl chloride and bromide, thionyl fluoride is not useful in organofluorine chemistry. The related derivative, sulfur tetrafluoride is however a useful reagent.


  1. Thionyl fluoride in Linstrom, P.J.; Mallard, W.G. (eds.) NIST Chemistry WebBook, NIST Standard Reference Database Number 69. National Institute of Standards and Technology, Gaithersburg MD. (retrieved 2014-05-11)
  2. 1 2 3
  3. "Safety (MSDS) data for thionyl fluoride". Oxford University. 2005-09-02. Retrieved 2008-07-29.
  4. Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  5. W. C. Smith, E. L. Muetterties "Thionyl Fluoride" Inorganic Syntheses 1960, Volume 6, pages: 162-163. doi:10.1002/9780470132371.ch50
  6. 1 2 3 Holleman, Arnold F. (2001). Inorganic Chemistry. Academic Press. p. 542. ISBN 0-12-352651-5. Retrieved 2008-07-29.
  7. Pepi, Federico; Andreina Ricci; Marco Di Stefano; Marzio Rosi; Giuseppe D'Arcangelo (September 18, 2002). "Thionyl Fluoride from Sulfur Hexafluoride Corona Discharge Decomposition: Gas-Phase Chemistry of (SOF2)H+ Ions". Journal of Physical Chemistry A. American Chemical Society. 106 (40): 9261–9266. doi:10.1021/jp021074v.
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