 In contrast to the many naturally-occurring organic compounds containing the heavier halides, chloride, bromide, and iodide, only a handful of biologically synthesized carbon-fluorine bonds are known.The most common natural organofluorine species is fluoroacetate, a toxin found in a few species of plants.Others include fluorooleic acid, fluoroacetone, nucleocidin (4'-fuoro-5'-O-sulfamoyladenosine), fluorothreonine, and 2-fluorocitrate.