Cyclopentadienyl is a chemical compound that consists of a five-membered carbon ring with two double bonds. Its structure allows it to act as a ligand, meaning it can bond to metal atoms in various chemical reactions. This property makes it important in organometallic chemistry. The cyclopentadienyl anion, formed when cyclopentadiene loses a proton, is particularly significant in the formation of metallocenes. These compounds, which include a metal atom sandwiched between two cyclopentadienyl anions, are used in various applications, including catalysis and materials science.