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) Tri-alkyl mono-aryl ammonium (F414200) Di-alkyl di-aryl ammonium (F414300) Pyridine ammonium (F414500) Sulfur Phosphorus Halogen Boron Magnesium Silicon Iron Cobalt Asenic Selenium Tin