In chemistry, disulfate or pyrosulfate is the anion with the molecular formula [S2O7]2−. Disulfate is the IUPAC name. [1] It has a dichromate like structure and can be visualised as two corner sharing SO4 tetrahedra, with a bridging oxygen atom.[2] In this compound sulfur has an oxidation state of +6. Disulfate is the conjugate base of the hydrogen disulfate (hydrogen pyrosulfate) ion HS2O7-, which in turn is the conjungate base of disulfuric acid (pyrosulfuric acid).