FGROUP by class
Carbon Carbon skeleton Hydrocarbon ring N-heterocyclic O-heterocyclic S-heterocyclic Mixed-heterocyclic Oxygen Nitrogen Amine (F410000) Quaternary ammonium (F414000) Tetra-alkyl ammonium (F414100) Trimethyl methylene ammonium (F414101) Sulfur Phosphorus Halogen Boron Magnesium Silicon Iron Cobalt Asenic Selenium Tin