ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI%3DInChI%3D1S/Mg.O2/c%3B1-2/q%202%3B-2/file?format=sdf&get3d=True -- InChI%3DInChI%3D1S/Mg.O2/c%3B1-2/q%202%3B-2 could not be loaded.