CoC5H52

CoC5H52, commonly known as cobaltocene or bis(cyclopentadienyl)cobalt, is an organometallic compound with the formula Co(C5H5)2 (often abbreviated CoCp2). It is a metallocene in which a cobalt atom is sandwiched between two parallel η5-cyclopentadienyl rings, giving a neutral complex that corresponds to cobalt in the +2 oxidation state and a 19-electron metal framework.

Structure and bonding: The two cyclopentadienyl rings donate electron density to the cobalt center in an η5 fashion, creating a sandwich geometry characteristic of metallocenes. In solid samples the rings are typically arranged in a staggered orientation, and the compound is soluble in nonpolar organic solvents such as toluene or hexane. The 19-electron count reflects the combination of the cobalt d-electrons and the electron donation from the two Cp ligands.

Synthesis: Cobaltocene is prepared by reducing cobalt(II) precursors in the presence of cyclopentadienyl sources, often via salt metathesis or reductive routes that furnish Cp2Co. Because it is air- and moisture-sensitive, syntheses and handling are conducted under inert atmosphere conditions.

Properties and reactivity: Cobaltocene is an air-sensitive, paramagnetic compound due to its odd electron count. It functions as a one-electron reducing agent and can be oxidized to the cobaltocenium cation, [Co(C5H5)2]+. The compound participates in electron-transfer reactions and serves as a useful reagent in organometallic and redox chemistry studies.

Applications and safety: Used as a reagent in organic synthesis and as a model system in metallocene chemistry. Handling requires inert atmosphere and anhydrous conditions; exposure to air or moisture leads to decomposition. Proper precautions include protective equipment and storage under dry, oxygen-free conditions.