Selenium hexasulfide is a chemical compound with the chemical formula . Its molecular structure is an 8-membered ring, consisting of two selenium and six sulfur atoms (diselenacyclooctasulfane), analogous to the ring, an allotrope of sulfur (cyclooctasulfur or cyclooctasulfane), and other 8-membered rings of selenium sulfides with formula .
There are several isomers depending on the relative placement of the selenium atoms in the ring: 1,2-diselenacyclooctasulfane (with the two Se atoms adjacent), 1,3-diselenacyclooctasulfane, 1,4-diselenacyclooctasulfane, and 1,5-diselenacyclooctasulfane (with the Se atoms opposite).[1] It is an oxidizing agent.
The 1,2 isomer can be prepared by reaction of chlorosulfanes and dichlorodiselane with potassium iodide in carbon disulfide. The reaction produces also cyclooctaselenium and all other eight-member cyclic selenium sulfides, except selenacyclooctasulfane, and several six- and seven-membered rings.[2]