Dicarbonyl iron-alkyl complex

Dicarbonyl(ri5-cyclopentadienyl)iron-alky] complexes represent useful precursors for iron-carbene complexes [47]. For example, iron-carbene complexes are intermediates in the acid-promoted reaction of Fp-alkyl ether derivatives with alkenes to provide cyclopropanes via a [2 + l]-cycloaddition (Scheme 1.16). 

Alkyl iron complexes behave as electrophiles in the presence of nucleophiles. Rosenblum and co-worker showed, for example, that the ethene complex of cyclopentadienyl dicarbonyl iron (abbreviated as Fp), Fp-ethene (482), reacted with dimethyl lithiomalonate to give 486.3 4 Conjugated iron complexes can also be... 

Many other iron complexes (t -alkyls, t -acyls, t -ynyls, cationic -alkenes, and carbenes) are ultimately erived from either sodium dicarbonyl(cyclopentadienyl)... 

Addition of nucleophiles to alkene ligands of cationic dicarbonyl(cyclopenta-dienyl)iron complexes provides access to alkyl-Fp complexes (Scheme 4-20). Nucleophilic reagents may be enolates, silyl enol ethers, or organocuprates. ... 

Alternatively, acyliron complexes can be obtained in a two-step sequence either from dicarbonyl(cyclopentadienyl)ferrates or from dicarbonyl(cyclopentadienyl)iron halides via alkyl-Fp complexes. The first method makes use of the nucleophilicity of [CpFe(CO)2] anions. Their reaction with alkyl halides provides alkyl-Fp complexes that, upon treatment with phosphanes or phosphites, undergo a migratory insertion of a carbonyl ligand into the metal-alkyl bond leading to an acyliron complex (Scheme 4-38). " ... 

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