InChI=1S/C16H16O8S/c1-22-14-8-10(5-6-12(14)17)3-4-11-7-13(18)16(15(9-11)23-2)24-25(19,20)21/h3-9,17-18H,1-2H3,(H,19,20,21)/b4-3+