Polysulfides are a class of chemical compounds containing chains of sulfur atoms. There are two main classes of polysulfides: anions and organic polysulfides. Anions have the general formula S_n^2-. These anions are the conjugate bases of the hydrogen polysulfides H₂S_n. Organic polysulfides generally have the formulae RS_nR, where R = alkyl or aryl.