ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI%3DInChI%3D1S/C2F4.C2H4/c3-1%284%292%285%296%3B1-2/h%3B1-2H2/file?format=sdf&get3d=True -- InChI%3DInChI%3D1S/C2F4.C2H4/c3-1%284%292%285%296%3B1-2/h%3B1-2H2 could not be loaded.