ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C2H4N4O2/c3-1(7)5-6-2(4)8/h(H2,3,7)(H2,4,8)/file?format=sdf&get3d=True  -- InChI=1S/C2H4N4O2/c3-1(7)5-6-2(4)8/h(H2,3,7)(H2,4,8) could not be loaded.