ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C6H6N2/c1-6(5-8)3-2-4-7/h1-3H2/file?format=sdf&get3d=True  -- InChI=1S/C6H6N2/c1-6(5-8)3-2-4-7/h1-3H2 could not be loaded.