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