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(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.

Scope edit

 
structure of the Fe(CO)3 adduct of vitamin A aldehyde.[1]

The inventory of complexes is large.

Selected (diene)Fe(CO)3 Complexes
diene CAS RN physical properties notes
(cyclobutadiene)Fe(CO)3 12078-17-0 orange solid, b.p. 47 °C (3 mm) antiaromatic ligand[2]
(butadiene)Fe(CO)3 12078-32-9 yellow-orange, m.p. 19 °C major prototype
(Isoprene)Fe(CO)3 32731-93-4 yellow liquid chiral[3]
(1,3-Cyclohexadiene)Fe(CO)3 12252-72-6 yellow, m.p. 8-9 °C major prototype for steroidal and terpenoid derivatives[4]
(norbornadiene)Fe(CO)3 12307-07-2 yellow, m.p. -2 °C non-conjugated diene[5]
(norbornadienone)Fe(CO)3 12307-01-6 yellow, m.p. 93-95 °C free diene-one is unstable[6]
(1,5-Cyclooctadiene)Fe(CO)3 12093-20-8 yellow, m.p. 76 °C non-conjugated diene[7][8]
(1,3-Cyclooctadiene)Fe(CO)3 33270-50-7 yellow, m.p. 36 °C isomeric with 1,5-cyclooctadiene derivative[7][9]
(η4-Thiepine)Fe(CO)3 - yellow, , m.p. 54.5-55 °C chiral, thiepine = cyclo-C6H6S, which is antiaromatic[10]

Preparation and uses edit

Many of diene complexes were originally prepared by reaction of iron pentacarbonyl with the diene under UV-radiation. Often yields are modest because the complexes, which are often liquids, volatilize during workup.[5] Some derivatives derivatives are prepared displacement of bda from (benzylideneacetone)iron tricarbonyl (Fe(bda)(CO)3)[11]

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.[12]

These complexes are mainly of academic interest. Some iron tricarbon complexes of cyclopentadienones catalyze hydrogenation, see Knolker complex.

Characterization edit

 
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.[13]

References edit

  1. ^ 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.
  2. ^ Pettit, R.; Henery, J. (1970). "Cyclobutadieneiron Tricarbonyl". Organic Syntheses. 50: 21. doi:10.15227/orgsyn.050.0021.
  3. ^ 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.
  4. ^ Pearson, Anthony J.; Sun, Huikai (2008). "Cyclohexadieneiron Tricarbonyl". e-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn00791. ISBN 978-0471936237.
  5. ^ a b 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.
  6. ^ 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.
  7. ^ a b 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.
  8. ^ 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.
  9. ^ 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.
  10. ^ 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.
  11. ^ 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. pp. 52–55. doi:10.1002/9780470132593.ch11. ISBN 9780470132593.
  12. ^ 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.
  13. ^ 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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