Ferro­cene

Other names: bis(η⁵-cyclo­pentadienyl)iron, iron(II) cyclo­penta­dienide, FeCp₂, Fc

C₁₀H₁₀Fe

32/50 uncommon

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.