Other names: bis(η5-cyclopentadienyl)iron, iron(II) cyclopentadienide, FeCp2, Fc
Ferrocene is the archetypal metallocene, sometimes called a "sandwich complex". It consists of an Fe2+ ion bound between two aromatic cyclopentadienyl anions. The bonding interaction occurs equally from every carbon atom in the cyclopentadienide ligands, through a phenomenon known as hapticity. In addition to being aesthetically pleasing, ferrocene is frequently used in electrochemistry to provide a well-defined internal reference associated with the Fc/Fc+ redox couple.