page_title: Organoiron chemistry
section_title: Tri- and polyene Fe(0) complexes
hierarchical_section_title: Organoiron chemistry / Iron(0) and more reduced states / Tri- and polyene Fe(0) complexes
context_page_description: Organoiron chemistry is the chemistry of iron compounds containing a carbon-to-iron chemical bond. Organoiron compounds are relevant in organic synthesis as reagents such as iron pentacarbonyl, diiron nonacarbonyl and disodium tetracarbonylferrate. Iron adopts oxidation states from Fe through to Fe(VII). Although iron is generally less active in many catalytic applications, it is less expensive and "greener" than other metals. Organoiron compounds feature a wide range of ligands that support the Fe-C bond; as with other organometals, these supporting ligands prominently include phosphines, carbon monoxide, and cyclopentadienyl, but hard ligands such as amines are employed as well.
context_section_description: Stable iron-containing complexes with and without CO ligands are known for a wide variety of polyunsaturated hydrocarbons, e.g. cycloheptatriene,  azulene, and bullvalene. In the case of cyclooctatetraene (COT), derivatives include Fe(COT)₂, Fe₃(COT)₃, and several mixed COT-carbonyls (e.g. Fe(COT)(CO)₃ and Fe₂(COT)(CO)₆).
caption: Bis(cyclooctatetraene)iron is an Fe(0) complex lacking CO ligands.