ERROR opening https://cactus.nci.nih.gov/chemical/structure/CN1C2%3DC%28C%28%3DO%29N%28C1%3DO%29C%29NC%3DN2/file?format=sdf&get3d=True  -- CN1C2%3DC%28C%28%3DO%29N%28C1%3DO%29C%29NC%3DN2 could not be loaded.