Chemistry:Flyover complex

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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.

Structure of an asymmetrical flyover complex (C5H5)2Fe2[(CCF3)4CO]CO. The Fe-Fe bond length is 258.8 picometers.[1]

Common examples are the iron carbonyl derivatives, which are typically air-stable, soluble in nonpolar solvents, and red-orange in color.[2] 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.[3]

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).[4] [5]

References

  1. Davidson, John L.; Green, Michael; Stone, F. Gordon A.; Welch, Alan J. (1976). "Insertion Reactions of Hexafluorobut-2-yne, Tetrafluoroethylene, and Hexafluoroacetone with η5-Cyclopentadienyl-Iron, -Ruthenium, -Palladium, and -Molybdenum Complexes; Molecular and Crystal Structures of [Fe2(CO){C4(CF3)4CO}(η5-C5H5)2] and [Fe{COCF2C5H5}(η5-C5H5)]". J. Chem. Soc., Dalton Trans. (20): 2044–2053. doi:10.1039/dt9760002044. 
  2. Fehlhammer, W.P.; Stolzenberg, H. (1982). "Dinuclear Iron Compounds with Hydrocarbon Ligands". Comprehensive Organometallic Chemistry. pp. 513–613. doi:10.1016/B978-008046518-0.00051-9. ISBN 9780080465180. 
  3. Organic Syntheses via Metal Carbonyls Volume 1. NY: Wiley Interscience. 1968. 
  4. Giordano, Roberto; Sappa, Enrico; Cauzzi, Daniele; Predieri, Giovanni; Tiripicchio, Antonio (1996). "Reactions of the 'Ferrole' Complex [Fe2(CO)6(C2Et2)2] with Group 15 Donor Ligands and with Alkynes. Stepwise Formation and Disengagement of Tropones. Crystal and Molecular Structure of [Fe2(CO)5{(CEt)2CO(CEt)2CHCPh}]". Journal of Organometallic Chemistry 511 (1–2): 263–271. doi:10.1016/0022-328X(95)05936-J. 
  5. Fagan, Paul J. (1995). "Dinuclear Iron Compounds with Hydrocarbon Ligands". Comprehensive Organometallic Chemistry II. pp. 231–258. doi:10.1016/B978-008046519-7.00058-7. ISBN 9780080465197.