FGROUP by class
Carbon Carbon skeleton Hydrocarbon ring N-heterocyclic O-heterocyclic S-heterocyclic Mixed-heterocyclic Oxygen Nitrogen Sulfur Mercaptan (F510000) Thiol (F510000) Alkyl thiol (F511000) Allyl thiol (F512000) Acetylene thiol (F513000) Thiophenol (F514000) Aryl thiol (F514000) Thiol sulfide (F515000) Phosphorus Halogen Boron Magnesium Silicon Iron Cobalt Asenic Selenium Tin