Disulfur decafluoride

Disulfur decafluoride (S2F10) is a gas discovered in 1934 by Denbigh and Whytlaw-Gray. Each S of the S2F10 molecule is octahedral, and surrounded by 5 fluorines. S2F10 is highly toxic, with toxicity 4 times that of phosgene. It was considered a potential chemical warfare pulmonary agent in World War II because it does not produce lacrimation or skin irritation, thus providing little warning of exposure. It is produced by the electrical decomposition of sulfur hexafluoride (SF6)—an essentially inert insulator used in high voltage systems such as transmission lines, substations and switchgear. S2F10 is also made during the production of SF6, but is distilled out.

Production
Disulfur decafluoride is produced primarily by the decomposition of sulfur hexafluoride:

2 SF6 → S2F10 + F2

Properties
This compound contains sulfur in the +5 oxidation state.

At temperatures above 150°C, decomposes slowly to  and :

S2F10 → SF6 + SF4

reacts with to give. It reacts with to form  in the presence of ultraviolet radiation.

In the presence of excess chlorine gas, reacts to form sulfur chloride pentafluoride :


 * + → 2

The analogous reaction with bromine is reversible and yields. The reversibility of this reaction can be used to synthesize from.

Ammonia is oxidised by into Thiazyl trifluoride.

Toxicity
Sulfur pentafluoride is a colorless gas or liquid with a sulfur-dioxide-like odor. It is about 4 times as poisonous as phosgene. Its toxicity is thought to be caused by its disproportionation in the lungs into, which is inert, and , which reacts with moisture to form sulfurous acid and hydrofluoric acid. Disulfur decafluoride itself is not toxic due to hydrolysis products, since it is hardly hydrolysed by water and most aqueous solutions.