ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C5H6N2/c1-2-4-7-5-6-3-1/h1-4H,5H2/file?format=sdf&get3d=True  -- InChI=1S/C5H6N2/c1-2-4-7-5-6-3-1/h1-4H,5H2 could not be loaded.