Sulfide - Disulfides

Disulfides

Confusion arises from the different meanings of the term "disulfide". Molybdenum disulfide (MoS₂) consists of separated sulfide centers, in association with molybdenum in the formal 4+ oxidation state (Mo4+). Iron disulfide (pyrite, FeS₂) on the other hand consists of S₂2−, or −S–S− dianion, in association with divalent iron in the formal 2+ oxidation state (ferrous ion: Fe2+). Dimethyldisulfide has the chemical binding CH₃-S–S-CH₃, whereas carbon disulfide has no S–S bond, being S=C=S (linear molecule analog to CO₂). Most often in sulfur chemistry and in biochemistry, the disulfide term is commonly ascribed to the sulfur analogue of the peroxide −O–O− bond. The disulfide bond (−S–S−) plays a major role in the conformation of proteins and in the catalytic activity of enzymes.