ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C6H8N2/c7-5-1-2-6(8)4-3-5/h1-4H,7-8H2/file?format=sdf&get3d=True  -- InChI=1S/C6H8N2/c7-5-1-2-6(8)4-3-5/h1-4H,7-8H2 could not be loaded.