Ferricin

Ferricin is a metallocene compound with the chemical formula Fe(C5H5)2. It consists of a central iron atom sandwiched between two cyclopentadienyl rings. Ferricin is a highly stable, bright orange, crystalline solid. It is soluble in many organic solvents but insoluble in water. The compound is often referred to as ferrocene, and ferricin is its less common systematic name.

Ferrocene was first synthesized in 1951, independently by Kealy and Pauson and by Miller and coworkers. Its discovery revolutionized organometallic chemistry due to its unusual sandwich structure, which was later confirmed by X-ray crystallography and explained by the concept of aromaticity in organometallic compounds. The iron atom in ferrocene is in the +2 oxidation state.

Ferrocene exhibits a rich chemistry, undergoing electrophilic substitution reactions on the cyclopentadienyl rings, similar to aromatic hydrocarbons. It is used as a catalyst in various organic transformations, as an additive in fuels to improve combustion, and in the development of redox-active polymers and materials. Its electrochemical properties also make it valuable in electrochemistry and as a reference standard.