Thiothionyl fluoride

Thiothionyl fluoride is a chemical compound of fluorine and sulfur, with the chemical formula S\dSF2. It is an isomer of disulfur difluoride (difluorodisulfane) F\sS\sS\sF.

Preparation
Thiothionyl fluoride can be obtained from the reaction between disulfur dichloride with potassium fluoride at about 150 °C or with mercury(II) fluoride at 20 °C.


 * S2Cl2 + 2 KF → S\dSF2 + 2 KCl

Another possible preparation is by the reaction of nitrogen trifluoride with sulfur.


 * NF3 + 3 S → S\dSF2 + NSF

It also forms from disulfur difluoride when in contact with alkali metal fluorides.

S\dSF2 can also be synthesized with the reaction of potassium fluorosulfite and disulfur dichloride:


 * 2 KSO2F + S2Cl2 → S\dSF2 + 2 KCl + 2 SO2

Properties
Thiothionyl fluoride is a colorless gas. At high temperatures and pressures, it decomposes into sulfur tetrafluoride and sulfur.


 * 2 S\dSF2 → SF4 + 3 S

With hydrogen fluoride, it forms sulfur tetrafluoride and hydrogen sulfide.


 * S\dSF2 + 2 HF → SF4 + H2S

It condenses with sulfur difluoride at low temperatures to yield 1,3-difluoro-trisulfane-1,1-difluoride.
 * S\dSF2 + SF2 → FS\sS\sSF3