InChI=1S/C16H18O9S/c1-6-2-3-8(26-6)4-7-5-9(15(22)23-7)24-16-12(19)10(17)11(18)13(25-16)14(20)21/h2-4,9-13,16-19H,5H2,1H3,(H,20,21)/b7-4+