Thionyl fluoride

Thionyl fluoride

Names
IUPAC name Thionyl fluoride
Identifiers
CAS Number	7783-42-8
ChemSpider	22954
Jmol interactive 3D	Image
PubChem	24548
InChI InChI=1S/F2OS/c1-4(2)3 Key: LSJNBGSOIVSBBR-UHFFFAOYSA-N InChI=1/F2OS/c1-4(2)3 Key: LSJNBGSOIVSBBR-UHFFFAOYAL
SMILES FS(F)=O
Properties
Chemical formula	F2OS
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 in water	hydrolysis
Solubility	soluble in ethanol, ether, benzene
Vapor pressure	75.7 kPa (-50 °C)[1]
Structure
Molecular shape	trigonal pyramidal
Thermochemistry
Std molar entropy (S^o298)	278.6 J/mol·K[2]
Std enthalpy of formation (ΔfH^o298)	-715 kJ/mol[2]
Std enthalpy of combustion (ΔcH^o298)	56.8 J/mol·K[2]
Hazards
EU classification (DSD)	T C
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 C_s 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.

References

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. http://webbook.nist.gov (retrieved 2014-05-11)
2. http://chemister.ru/Database/properties-en.php?dbid=1&id=8280
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. 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.

External links