Flyover complex
In organometallic chemistry, a flyover complex features two metals bridged by the fragment OC2. Some flyover complexes are symmetrical and some are not.
File:Cp2Fe2CO CPFMFX10.png|thumb|Structure of an asymmetrical flyover complex 2Fe2CO. The Fe-Fe bond length is 258.8 picometers.
Common examples are the iron carbonyl derivatives, which are typically air-stable, soluble in nonpolar solvents, and red-orange in color. These diiron complexes arise by the reaction of alkynes with iron carbonyls. Such reactions are known to generate many products, e.g. complexes of cyclopentadienones and para-quinones.
Some ferrole complexes react with tertiary phosphines to give the substituted flyover complex Fe25. They insert alkynes en route to tropones.