FGROUP by class
Carbon Carbon skeleton Hydrocarbon ring N-heterocyclic O-heterocyclic S-heterocyclic Mixed-heterocyclic Oxygen Nitrogen Imine (F420000) Hydroxylimine (F424000) Oxime (F424000) Aldoxime (F424100) Ketoxime (F424200) Sulfur Phosphorus Halogen Boron Magnesium Silicon Iron Cobalt Asenic Selenium Tin