FGROUP by class
Carbon Carbon skeleton Hydrocarbon ring N-heterocyclic O-heterocyclic S-heterocyclic Mixed-heterocyclic Oxygen Nitrogen Sulfur Mercaptan (F510000) Thiol (F510000) Sulfamate (F581000) Sulfamic acid (F581100) Sulfamate ester (F581200) Phosphorus Halogen Boron Magnesium Silicon Iron Cobalt Asenic Selenium Tin