(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]
(1,5-Cyclooctadiene)Fe(CO)312093-20-8yellow, m.p. 76 °Cnon-conjugated diene [8] [9]
(1,3-Cyclooctadiene)Fe(CO)333270-50-7yellow, m.p. 36 °Cisomeric with 1,5-cyclooctadiene derivative [8] [10]
4-Thiepine)Fe(CO)3-yellow, , m.p. 54.5-55 °Cchiral, thiepine = cyclo-C6H6S, which is antiaromatic [11]

Preparation and uses

Many of diene complexes were originally prepared by reaction of iron pentacarbonyl with the diene under UV-radiation. In some cases, 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) [12]

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. [13]

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. [14]

Related Research Articles

Cyclohexa-1,3-diene is an organic compound with the formula (C2H4)(CH)4. It is a colorless, flammable liquid. Its refractive index is 1.475 (20 °C, D). It is one of two isomers of cyclohexadiene, the other being 1,4-cyclohexadiene.

<span class="mw-page-title-main">Olefin metathesis</span> Organic reaction involving the breakup and reassembly of alkene double bonds

In organic chemistry, olefin metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the scission and regeneration of carbon-carbon double bonds. Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative organic reactions. For their elucidation of the reaction mechanism and their discovery of a variety of highly active catalysts, Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock were collectively awarded the 2005 Nobel Prize in Chemistry.

<span class="mw-page-title-main">Cyclooctatetraene</span> Chemical compound

1,3,5,7-Cyclooctatetraene (COT) is an unsaturated derivative of cyclooctane, with the formula C8H8. It is also known as [8]annulene. This polyunsaturated hydrocarbon is a colorless to light yellow flammable liquid at room temperature. Because of its stoichiometric relationship to benzene, COT has been the subject of much research and some controversy.

<span class="mw-page-title-main">Iron pentacarbonyl</span> Chemical compound

Iron pentacarbonyl, also known as iron carbonyl, is the compound with formula Fe(CO)5. Under standard conditions Fe(CO)5 is a free-flowing, straw-colored liquid with a pungent odour. Older samples appear darker. This compound is a common precursor to diverse iron compounds, including many that are useful in small scale organic synthesis.

1,5-Cyclooctadiene is a cyclic hydrocarbon with the chemical formula C8H12, specifically [−(CH2)2−CH=CH−]2.

<span class="mw-page-title-main">Cyclobutadieneiron tricarbonyl</span> Chemical compound

Cyclobutadieneiron tricarbonyl is an organoiron compound with the formula Fe(C4H4)(CO)3. It is a yellow oil that is soluble in organic solvents. It has been used in organic chemistry as a precursor for cyclobutadiene, which is an elusive species in the free state.

Osmium compounds are compounds containing the element osmium (Os). Osmium forms compounds with oxidation states ranging from −2 to +8. The most common oxidation states are +2, +3, +4, and +8. The +8 oxidation state is notable for being the highest attained by any chemical element aside from iridium's +9 and is encountered only in xenon, ruthenium, hassium, iridium, and plutonium. The oxidation states −1 and −2 represented by the two reactive compounds Na
2
[Os
4
(CO)
13
]
and Na
2
[Os(CO)
4
]
are used in the synthesis of osmium cluster compounds.

<span class="mw-page-title-main">Triiron dodecacarbonyl</span> Chemical compound

Triiron dodecacarbonyl is the organoiron compound with the formula Fe3(CO)12. It is a dark green solid that sublimes under vacuum. It is soluble in nonpolar organic solvents to give intensely green solutions. Most low-nuclearity clusters are pale yellow or orange. Hot solutions of Fe3(CO)12 decompose to an iron mirror, which can be pyrophoric in air. The solid decomposes slowly in air, and thus samples are typically stored cold under an inert atmosphere. It is a more reactive source of iron(0) than iron pentacarbonyl.

<span class="mw-page-title-main">Diiron nonacarbonyl</span> Chemical compound

Diiron nonacarbonyl is an organometallic compound with the formula Fe2(CO)9. This metal carbonyl is an important reagent in organometallic chemistry and of occasional use in organic synthesis. It is a more reactive source of Fe(0) than Fe(CO)5. This micaceous orange solid is virtually insoluble in all common solvents.

<span class="mw-page-title-main">(Benzylideneacetone)iron tricarbonyl</span> Chemical compound

(Benzylideneacetone)iron tricarbonyl is the organoiron compound with the formula (C6H5CH=CHC(O)CH3)Fe(CO)3. It is a reagent for transferring the Fe(CO)3 unit. This red-colored compound is commonly abbreviated (bda)Fe(CO)3.

<span class="mw-page-title-main">Triosmium dodecacarbonyl</span> Chemical compound

Triosmium dodecacarbonyl is a chemical compound with the formula Os3(CO)12. This yellow-colored metal carbonyl cluster is an important precursor to organo-osmium compounds. Many of the advances in cluster chemistry have arisen from studies on derivatives of Os3(CO)12 and its lighter analogue Ru3(CO)12.

<span class="mw-page-title-main">Triruthenium dodecacarbonyl</span> Chemical compound

Triruthenium dodecacarbonyl is the chemical compound with the formula Ru3(CO)12. Classified as metal carbonyl cluster, it is a dark orange-colored solid that is soluble in nonpolar organic solvents. The compound serves as a precursor to other organoruthenium compounds.

Organoiron chemistry is the chemistry of iron compounds containing a carbon-to-iron chemical bond. Organoiron compounds are relevant in organic synthesis as reagents such as iron pentacarbonyl, diiron nonacarbonyl and disodium tetracarbonylferrate. Although iron is generally less active in many catalytic applications, it is less expensive and "greener" than other metals. Organoiron compounds feature a wide range of ligands that support the Fe-C bond; as with other organometals, these supporting ligands prominently include phosphines, carbon monoxide, and cyclopentadienyl, but hard ligands such as amines are employed as well.

<span class="mw-page-title-main">Organoruthenium chemistry</span>

Organoruthenium chemistry is the chemistry of organometallic compounds containing a carbon to ruthenium chemical bond. Several organoruthenium catalysts are of commercial interest and organoruthenium compounds have been considered for cancer therapy. The chemistry has some stoichiometric similarities with organoiron chemistry, as iron is directly above ruthenium in group 8 of the periodic table. The most important reagents for the introduction of ruthenium are ruthenium(III) chloride and triruthenium dodecacarbonyl.

A metal carbido complex is a coordination complex that contains a carbon atom as a ligand. They are analogous to metal nitrido complexes. Carbido complexes are a molecular subclass of carbides, which are prevalent in organometallic and inorganic chemistry. Carbido complexes represent models for intermediates in Fischer–Tropsch synthesis, olefin metathesis, and related catalytic industrial processes. Ruthenium-based carbido complexes are by far the most synthesized and characterized to date. Although, complexes containing chromium, gold, iron, nickel, molybdenum, osmium, rhenium, and tungsten cores are also known. Mixed-metal carbides are also known.

<span class="mw-page-title-main">Half sandwich compound</span> Class of coordination compounds

Half sandwich compounds, also known as piano stool complexes, are organometallic complexes that feature a cyclic polyhapto ligand bound to an MLn center, where L is a unidentate ligand. Thousands of such complexes are known. Well-known examples include cyclobutadieneiron tricarbonyl and (C5H5)TiCl3. Commercially useful examples include (C5H5)Co(CO)2, which is used in the synthesis of substituted pyridines, and methylcyclopentadienyl manganese tricarbonyl, an antiknock agent in petrol.

<span class="mw-page-title-main">Transition metal nitrile complexes</span> Class of coordination compounds containing nitrile ligands (coordinating via N)

Transition metal nitrile complexes are coordination compounds containing nitrile ligands. Because nitriles are weakly basic, the nitrile ligands in these complexes are often labile.

<span class="mw-page-title-main">(Butadiene)iron tricarbonyl</span> Chemical compound

(Butadiene)iron tricarbonyl is an organoiron compound with the formula (C4H6)Fe(CO)3. It is a well-studied metal complex of butadiene. An orange-colored viscous liquid that freezes just below room temperature, the compound adopts a piano stool structure.

<span class="mw-page-title-main">Transition metal isocyanide complexes</span> Class of chemical compounds

Transition metal isocyanide complexes are coordination compounds containing isocyanide ligands. Because isocyanides are relatively basic, but also good pi-acceptors, a wide range of complexes are known. Some isocyanide complexes are used in medical imaging.

Trimethylenemethane complexes are metal complexes of the organic compound trimethylenemethane. Several examples are known, and some have been employed in organic synthesis.

References

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