Disulfite

A disulfite, commonly known as metabisulfite or pyrosulfite, is a chemical compound containing the disulfite ion (metabisulfite ion) S2O2−5. A disulfite, commonly known as metabisulfite or pyrosulfite, is a chemical compound containing the disulfite ion (metabisulfite ion) S2O2−5. Surprisingly, and in contrast to disulfate (S2O2−7), disulfite ion (S2O2−5) has two directly connected sulfur atoms, and the structure is described as 'thionite-thionate', or 2−, instead of the symmetrical form 2−.