Flyover complex

File:Flyover complex.svg

Structure of the flyover complex Fe₂(C₄H₄CO)(CO)₆, which has idealized C₂-symmetry.

In organometallic chemistry, a flyover complex features two metals bridged by the fragment OC(RC=CR)₂. Some flyover complexes are symmetrical and some are not.

File:Cp2Fe2(C4(CF3)4CO)CO CPFMFX10.png

Structure of an asymmetrical flyover complex (C₅H₅)₂Fe₂[(CCF₃)₄CO]CO. 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 Fe₂(CO)₅(PR₃)(C₄R₄CO). They insert alkynes en route to tropones (R₆C₇O).