Wiktionary
cyclopentadienyl complex
n. (context chemistry English) an organometallic compound formed from cyclopentadiene (or a derivative) and a transition element or other metal
Wikipedia
Cyclopentadienyl complex
A cyclopentadienyl complex is a metal complex with one or more cyclopentadienyl groups (, abbreviated as Cp). Based on the type of bonding between the metals and the cyclopentadienyl moieties, cyclopentadienyl complexes are classified into the following three categories: a) π-complexes, b) σ-complexes, and c) ionic complexes.