ERROR opening https://cactus.nci.nih.gov/chemical/structure/CN%28CCOP%28%3DO%29%28O%29O%29C%28%3DN%29N/file?format=sdf&get3d=True  -- CN%28CCOP%28%3DO%29%28O%29O%29C%28%3DN%29N could not be loaded.