ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C6H4N2O4/c9-7(10)5-2-1-3-6(4-5)8(11)12/h1-4H/file?format=sdf&get3d=True  -- InChI=1S/C6H4N2O4/c9-7(10)5-2-1-3-6(4-5)8(11)12/h1-4H could not be loaded.