Making SI2 ?

[Anders Hoveland]

“Disulfur diiodide, S2I2, can be synthesized by the reaction of S2Cl2 with HI in CCl4 at room temperature, or better, by the reaction of HI with S2Cl2 in Freon at −78°C. en hyphen deg . In the latter case, it is obtained as a solid, which slowly decomposes to sulfur (especially S6, S7 and S8) and iodine above −30°C. The compound sulfur diiodide does not exist. Although iodine does not react with sulfur, these elements do form compounds in solution in AsF5/SO2.”

Inorganic chemistry. Egon Wiberg, Nils Wiberg, Arnold Frederick Holleman

 

I was thinking about what possible routes there might be to potentially making sulfur diiodide, since this simple compound is apparently so elusive. I imagine researchers have already attempted all the obvious routes.

 

What about reacting excess anhydrous hydrogen iodide with SF4 ?

 

The only fluroide of iodine that can be isolated is iodine pentafluoride. Presumably SF4 would not oxidize I2.

 

SF4 + (4)HI --> SI2 + I2 + (4)HF

 

The iodine could potentially ionize in the form of H2F[+] I[-], which could be problematic. Best to use at least 8 equivalents of HI for every 1 SF4.

 

What do you think would this work?

 

Other typical routes, such as SH2 with iodine, or SCl2 with HI, are destined for failure, because in the absence of water iodine is surprisingly more electropositive than sulfur, and vulnerable to oxidation because of its large atomic radius. Indeed, perhaps the hypothetical compound should be referred to as "diiodine sulfide".