FGROUP by class
Carbon Carbon skeleton Hydrocarbon ring N-heterocyclic O-heterocyclic S-heterocyclic Mixed-heterocyclic Oxygen Nitrogen Sulfur Mercaptan (F510000) Thiol (F510000) Allyl thiol (F512000) Primary allyl thiol (F512100) Secondary allyl thiol (F512200) Phosphorus Halogen Boron Magnesium Silicon Iron Cobalt Asenic Selenium Tin