ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/H4N4/c1-3-4-2/h(H2,1,4)(H2,2,3)/file?format=sdf&get3d=True  -- InChI=1S/H4N4/c1-3-4-2/h(H2,1,4)(H2,2,3) could not be loaded.