InChI=1S/C20H20O12S/c21-12-7-11(2-1-10-3-5-13(6-4-10)32-33(27,28)29)8-14(9-12)30-20-17(24)15(22)16(23)18(31-20)19(25)26/h1-9,15-18,20-24H,(H,25,26)(H,27,28,29)/b2-1+