(Diene)iron tricarbonyl

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In organometallic chemistry, (diene)iron tricarbonyl describes a diverse family of related coordination complexes consisting of a diene ligand coordinated to a Fe(CO)3 center. Often the diene is conjugated, e.g., butadiene, but the family includes nonconjugated dienes as well. The compounds are yellow, air-stable, often low-melting, and soluble in hydrocarbon solvents. The motif is so robust that even unstable dienes form easily characterized derivatives, such as norbornadienone and cyclobutadiene. [1]

Contents

Scope

structure of the Fe(CO)3 adduct of vitamin A aldehyde. VitaminAaldehydeFe(CO)3.svg
structure of the Fe(CO)3 adduct of vitamin A aldehyde.

The inventory of complexes is large.

Selected (diene)Fe(CO)3 Complexes
dieneCAS RNphysical propertiesnotes
(cyclobutadiene)Fe(CO)3 12078-17-0orange solid, b.p. 47 °C (3 mm) antiaromatic ligand [3]
(butadiene)Fe(CO)3 12078-32-9yellow-orange, m.p. 19 °Cmajor prototype
(Isoprene)Fe(CO)332731-93-4yellow liquidchiral [4]
(1,3-Cyclohexadiene)Fe(CO)312252-72-6yellow, m.p. 8-9 °Cmajor prototype for steroidal and terpenoid derivatives [5]
(norbornadiene)Fe(CO)312307-07-2yellow, m.p. -2 °Cnon-conjugated diene [6]
(norbornadienone)Fe(CO)312307-01-6yellow, m.p. 93-95 °Cfree diene-one is unstable [7]
(xylylene)Fe(CO)3, m.p. 39 °Cyellowfree diene is unstable [8]
(1,5-Cyclooctadiene)Fe(CO)312093-20-8yellow, m.p. 76 °Cnon-conjugated diene [9] [10]
(1,3-Cyclooctadiene)Fe(CO)333270-50-7yellow, m.p. 36 °Cisomeric with 1,5-cyclooctadiene derivative [9] [11]
(η4-Thiepine)Fe(CO)3-yellow, , m.p. 54.5-55 °Cchiral, thiepine = cyclo-C6H6S, which is antiaromatic [12]

Preparation and uses

Many of diene complexes were originally prepared by reaction of iron pentacarbonyl with the diene under UV-radiation:

Fe(CO)5 + diene → (diene)Fe(CO)3 + 2 CO

In some cases, isolated yields are modest because the complexes, which are often liquids, volatilize during workup. [6] Some derivatives derivatives are prepared displacement of bda from (benzylideneacetone)iron tricarbonyl (Fe(bda)(CO)3). [13] Addition of nucleophiles to (pentadienyl) iron tricarbonyl cations gives the neutral diene complex. [14] Diene complexes can also be produced by dehalogenation of 1,4-dihalobutene derivatives: [15]

Fe2(CO)9 + C6H4(CH2Br)2 → FeBr2 + (C6H4(=CH2)2)Fe(CO)3 + 6 CO

The Fe(CO)3 unit serves as a protecting group for the diene, preventing the diene from participating in Diels-Alder reactions and hydrogenation. The diene is usually deprotected with ceric ammonium nitrate. [16]

Reactions

These complexes participate in several reactions of potential value in organic synthesis. The dienes are susceptible to acylation using fairly standard Friedel-Crafts conditions. Once transformed, the diene can be removed with ceric ammonium nitrate as well as trimethylamine N-oxide. [1]

Some iron tricarbon complexes of cyclopentadienones catalyze hydrogenation, see Knolker complex.

Characterization

Sample of (butadiene)Fe(CO)3, illustrating the color typical of this family of compounds. ButadieneFe(CO)3.jpg
Sample of (butadiene)Fe(CO)3, illustrating the color typical of this family of compounds.

IR spectra of these complexes show νCO bands near 2040 and 1969 cm−1. At low temperatures, the lower energy band splits, which has been interpreted as evidence for fluxionality on the IR timescale. [17]

References

  1. 1 2 Ingmar Bauer, Hans‐Joachim Knölker (2013). "The Chemistry of Diene–Iron and Dienyl–Iron Complexes". PATAI'S Chemistry of Functional Groups Organoiron Compounds. Wiley & Sons. doi:10.1002/9780470682531.pat0652.
  2. ↑ Mason, R.; Robertson, G. B. (1970). "Crystal and molecular structure of (Vitamin-A aldehyde)tricarbonyliron". Journal of the Chemical Society A: Inorganic, Physical, Theoretical: 1229. doi:10.1039/J19700001229.
  3. ↑ Pettit, R.; Henery, J. (1970). "Cyclobutadieneiron Tricarbonyl". Organic Syntheses. 50: 21. doi:10.15227/orgsyn.050.0021.
  4. ↑ King, R. B.; Manuel, T. A.; Stone, F. G. A. (1961). "Chemistry of the Metal Carbonyls—IX. Diene Complexes of Iron". Journal of Inorganic and Nuclear Chemistry. 16 (3–4): 233–239. doi:10.1016/0022-1902(61)80495-8.
  5. ↑ Pearson, Anthony J.; Sun, Huikai (2008). "Cyclohexadieneiron Tricarbonyl". e-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn00791. ISBN   978-0471936237.
  6. 1 2 Green, M. L. H.; Pratt, L.; Wilkinson, G. (1960). "206. Spectroscopic Studies of Some Organoiron Complexes". Journal of the Chemical Society (Resumed): 989. doi:10.1039/JR9600000989.
  7. ↑ Landesberg, Joseph M.; Sieczkowski, J. (1971). "Synthesis and Chemistry of Tricarbonyl(7-norbornadienone)iron". Journal of the American Chemical Society. 93 (4): 972–980. doi:10.1021/ja00733a032.
  8. ↑ Roth, W.R; Meier, J.D (1967). "o-Chinodimethan - und 2. 2-Dimethyl-iso-inden-eisen-tricarbonyl". Tetrahedron Letters. 8 (22): 2053–2058. doi:10.1016/S0040-4039(00)91011-6.
  9. 1 2 Deeming, A. J.; Ullah, S. S.; Domingos, A. J. P.; Johnson, B. F. G.; Lewis, J. (1974). "Reactivity of co-ordinated ligands. Part XX. Preparation and Reactions of Cyclo-octadiene Complexes of Iron, Ruthenium, and Osmium". Journal of the Chemical Society, Dalton Transactions (19): 2093. doi:10.1039/DT9740002093.
  10. ↑ Kruczynski, Leonard.; Takats, Josef. (1976). "Intramolecular Rearrangement in (.eta.-diene)tricarbonyliron and -Ruthenium Compounds. A Carbon-13 Nuclear Magnetic Resonance Study". Inorganic Chemistry. 15 (12): 3140–3147. doi:10.1021/ic50166a041.
  11. ↑ Lewis, J.; Cotton, F. A.; Deeming, A. J.; Josty, P. L.; Ullah, S. S.; Domingos, A. J. P.; Johnson, B. F. G. (1971). "Tricarbonyl(cyclooctadiene) Complexes of Iron(0), Ruthenium(0), and Osmium(0)". Journal of the American Chemical Society. 93 (18): 4624–4626. doi:10.1021/ja00747a066.
  12. ↑ Nishino, Keitaro; Takagi, Masanobu; Kawata, Teruhisa; Murata, Ichiro; Inanaga, Junji; Nakasuji, Kazuhiro (1991). "Thiepine-iron tricarbonyl: Stabilization of thermally labile parent thiepine by transition metal complexation". Journal of the American Chemical Society. 113 (13): 5059–5060. doi:10.1021/ja00013a051.
  13. ↑ Domingos, A. J. P.; Howell, J. A. S.; Johnson, B. F. G.; Lewis, J. (1990). "Reagents for the Synthesis of η-Diene Complexes of Tricarbonnyliron and Tricarbonylruthenium". Inorganic Syntheses. Vol. 28. pp. 52–55. doi:10.1002/9780470132593.ch11. ISBN   9780470132593.
  14. ↑ Ernst, Richard D. (1999). "Pentadienyl Ligands: Their Properties, Potential, and Contributions to Inorganic and Organometallic Chemistry". Comments on Inorganic Chemistry. 21 (4–6): 285–325. doi:10.1080/02603599908012010.
  15. ↑ Kerber, Robert C.; Ribakove, Everett C. (1991). "Formation of Iron Carbonyl Complexes of Reactive Polyenes from Dihalides involving the Free Polyene". Organometallics. 10 (8): 2848–2853. doi:10.1021/om00054a059.
  16. ↑ Donaldson, William A.; Chaudhury, Subhabrata (2009). "Recent Applications of Acyclic (Diene)iron Complexes and (Dienyl)iron Cations in Organic Synthesis". European Journal of Organic Chemistry. 2009 (23): 3831–3843. doi:10.1002/ejoc.200900141. PMC   3121309 . PMID   21709767.
  17. ↑ Turner, James J.; Bühl, Michael (2018). "Infrared Dynamics of Iron Carbonyl Diene Complexes". The Journal of Physical Chemistry A. 122 (14): 3497–3505. Bibcode:2018JPCA..122.3497T. doi:10.1021/acs.jpca.7b12309. hdl: 10023/16989 . PMID   29394061.
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