Cyclopentadienyliron dicarbonyl dimer

Cyclopentadienyliron dicarbonyl dimer (C10H10Fe2(CO)4) is an organometallic compound with the formula (η^5-C5H5)2Fe2(CO)4, often abbreviated as Cp2Fe2(CO)4. This compound is a common example of a sandwich compound, where two cyclopentadienyl anions (Cp) are bonded to a central iron (Fe) atom. The molecule is dimeric, consisting of two iron atoms bridged by two carbon monoxide (CO) ligands, with each iron atom also bonded to two CO ligands and a cyclopentadienyl ring in a piano-stool configuration.

Structure and Bonding

The structure of cyclopentadienyliron dicarbonyl dimer is characterized by a Fe2(CO)4 core, where the iron atoms are bridged by two CO ligands. Each iron atom adopts an octahedral coordination geometry, completed by a cyclopentadienyl ring and two terminal CO ligands. The Fe-CO and Fe-Cp bond lengths and angles are indicative of strong π-backbonding, where electron density is transferred from the iron d orbitals to the π* orbitals of the CO ligands, strengthening the Fe-CO bond and weakening the C-O bond.

Synthesis

Cyclopentadienyliron dicarbonyl dimer is typically synthesized by the reaction of cyclopentadiene with iron pentacarbonyl (Fe(CO)5) in the presence of a base. The reaction proceeds through the formation of cyclopentadienyliron dicarbonyl monomer, which then dimerizes to form the target compound.

Reactivity

This compound exhibits typical reactivity of organometallic complexes, including ligand substitution, oxidative addition, and reductive elimination reactions. It can undergo substitution of one or both CO ligands with other ligands, providing a pathway to a variety of derivatives. The compound is also a precursor to other organometallic complexes through reactions involving the cyclopentadienyl ligands.

Applications

Cyclopentadienyliron dicarbonyl dimer is used as a starting material in the synthesis of various organometallic compounds. Its derivatives are of interest in catalysis, materials science, and as models for studying the mechanisms of organometallic reactions.

Safety and Handling

Like many organometallic compounds, cyclopentadienyliron dicarbonyl dimer is air and moisture sensitive. It should be handled under an inert atmosphere, typically in a glovebox or using Schlenk techniques. The compound is also toxic and requires appropriate safety precautions during handling and storage.