ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C6H4N2/c7-5-6-3-1-2-4-8-6/h1-4H/file?format=sdf&get3d=True  -- InChI=1S/C6H4N2/c7-5-6-3-1-2-4-8-6/h1-4H could not be loaded.