InChI=1S/C21H28O17S/c22-6-12-16(28)19(38-39(31,32)33)21(8-23,36-12)37-20-18(30)17(29)15(27)13(35-20)7-34-14(26)4-2-9-1-3-10(24)11(25)5-9/h1-5,12-13,15-20,22-25,27-30H,6-8H2,(H,31,32,33)/b4-2+