Wiktionary
ferrocene
n. any of a class of metallocenes containing an iron atom between two cyclopentadienyl rings; especially the simplest of the class ''bis-cyclopentadienyl iron''
Wikipedia
Ferrocene
Ferrocene is an organometallic compound with the formula Fe(CH). It is the prototypical metallocene, a type of organometallic chemical compound consisting of two cyclopentadienyl rings bound on opposite sides of a central metal atom. Such organometallic compounds are also known as sandwich compounds. The rapid growth of organometallic chemistry is often attributed to the excitement arising from the discovery of ferrocene and its many analogues.