InChI=1S/C16H16O8S/c1-22-15-8-11(12(17)9-13(15)18)5-3-10-4-6-14(16(7-10)23-2)24-25(19,20)21/h3-9,17-18H,1-2H3,(H,19,20,21)/b5-3+