Disulfur difluoride

Disulfur difluoride is an inorganic compound with the chemical formula S₂F₂. It is a halide of sulfur.

Disulfur difluoride

Sulfur, S   Fluorine, F
Names
IUPAC name fluorosulfanyl thiohypofluorite
Other names Difluorodisulfane[1]
Identifiers
CAS Number	13709-35-8
3D model (JSmol)	Interactive image
ChemSpider	109926
PubChem CID	123323
CompTox Dashboard (EPA)	DTXSID60160058
InChI InChI=1S/F2S2/c1-3-4-2
SMILES FSSF
Properties
Chemical formula	S2F2
Molar mass	102.127 g/mol
Melting point	−133 °C (−207 °F; 140 K)
Boiling point	15 °C (59 °F; 288 K)
Related compounds
Related compounds	O2F2 H2S2 S2Cl2 S2Br2 S2I2 SF2
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Structure

Disulfur difluoride has a chain structure F−S−S−F. The angle between the F^a−S−S and S−S−F^b planes is 87.9°, while the angles of F^a−S−S and S−S−F^b are equivalent, and are equal to 108.3°. Both S−F bonds are equivalent and their length is 163.5 pm, while the length of the S−S bond is 189 pm. This structure is referred to as gauche, and is similar to H₂O₂.

There is a branched isomer of disulfur difluoride, thiothionyl fluoride, with the structure S=SF₂.

Synthesis

Silver(II) fluoride can fluorinate sulfur in a strictly dry container at 125 °C (257 °F; 398 K), and the reaction produces FS−SF:^[2]

S₈ + 8 AgF₂ → 4 S₂F₂ + 8 AgF

Reactions

Disulfur difluoride undergoes intramolecular rearrangement in the presence of fluorides of alkali metals, yielding the isomer S=SF₂:^[3]

FS−SF → S=SF₂

• Decomposing to sulfur tetrafluoride and sulfur when heated to 180 °C:

2 S₂F₂ → SF₄ + 3 S

• Hydrolysis:

2 S₂F₂ + 2 H₂O → SO₂ + 3 S + 4 HF

• Reacting with sulfuric acid at 80 °C:

S₂F₂ + 3 H₂SO₄ → 5 SO₂ + 2 HF + 2 H₂O

• Reacting with sodium hydroxide:

2 S₂F₂ + 6 NaOH → Na₂SO₃ + 3 S + 4 NaF + 3 H₂O

• Reacting with oxygen at high pressure, using nitrogen dioxide as a catalyst:

2 S₂F₂ + 5 O₂ → SOF₄ + 3 SO₃^[4][5][6]