Thionyl fluoride

Thionyl fluoride

Names
IUPAC name Thionyl fluoride
Identifiers
CAS Number	7783-42-8 N
ChemSpider	22954 Y
Jmol 3D model	Interactive image
PubChem	24548
InChI InChI=1S/F2OS/c1-4(2)3 Y Key: LSJNBGSOIVSBBR-UHFFFAOYSA-N Y 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)
Structure
Molecular shape	trigonal pyramidal
Thermochemistry
Std molar entropy (So298)	278.6 J/mol·K
Std enthalpy of formation (ΔfHo298)	-715 kJ/mol
Std enthalpy of combustion (ΔcHo298)	56.8 J/mol·K
Vapor pressure	{{{value}}}
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.

Synthesis and reactions

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

3 SOCl₂ + 2SbF₃ → 3SOF₂ + 2SbCl₃

Alternatively, it arises via the fluorination of sulfur dioxide:

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.

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

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.