Polysulfide

The polysulfides are salts containing linear anions of the S_n^2– type. They are formed by attack of the sulfide anion on elemental sulfur (S₈) or by oxidation of sulfides, thus joining two sulfur atoms.

Historically, ammonium polysulfides (NH₄)₂S_n played a role of some importance in the march of cations allowing the selective precipitation of a group of metals.

The reaction of polysulfides with sulfur chlorides (for example, dichlorodisulfane Cl–S–S–Cl) has also been used to obtain large sulfur cycles (cyclo-S_m; m > 8).

The blue color of lapiz lazuli is attributed to polysulfane radicals.