CYCLOPENTADIENONE complexes of several transition metal ions have been prepared by the reaction of hexa-fluoro-but-2-yne with the metal carbonyl or π-cyclopentadienyl metal carbonyl 1.

The MO description is used to explain the bonding and stability of a range of compounds, including main-group organometallics, hypervalent compounds and complexes with metal-ligand ¿-interactions.