Английская Википедия:(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

The inventory of complexes is large, and has been extended to steroidal and terpenoid substrates.

Selected (diene)Fe(CO)3 Complexes
diene CAS RN notes
norbornadiene 12307-07-2 liquid, -2 °C[1]
1,5-Cyclooctadiene 12093-20-8 see [2]
1,3-Cyclooctadiene 33270-50-7 One of two isomers of (cyclooctadiene)Fe(CO)3[3]
1,3-Butadiene 12078-32-9 19 °C, see (Butadiene)iron tricarbonyl
Isoprene 32731-93-4 liquid at RT, chiral[4]

Preparation

Many of diene complexes were originally prepared by reaction of iron pentacarbonyl with the diene in refluxing toluene or similar solvents. Often yields are modest because the complexes, which are often liquids, volatilize during workup.[1] Especially for thermally sensitive derivatives, displacement of bda from (Benzylideneacetone)iron tricarbonyl (Шаблон:Chem2) has been recommended.[5]

Characterization

IR spectra of these complexes show nCO bands at 2040 and 1969. At low temperatures, the lower energy band splits, which has been interpreted as evidence for fluxionality on the IR timescale.[6]

Reactions

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.[7]

References