ERROR opening https://cactus.nci.nih.gov/chemical/structure/C1%3DCN%28C%3DN1%29C%28%3DS%29N2C%3DCN%3DC2/file?format=sdf&get3d=True  -- C1%3DCN%28C%3DN1%29C%28%3DS%29N2C%3DCN%3DC2 could not be loaded.