InChI=1S/C13H18N2O7S/c14-6-5-11(22-23(19,20)21)8-15-13(18)4-2-9-1-3-10(16)7-12(9)17/h1-4,7,11,16-17H,5-6,8,14H2,(H,15,18)(H,19,20,21)/b4-2+