metallocene
metallocene
Organometallic coordination compounds in which one atom of a transition metal such as iron, ruthenium or osmium is bonded to and only to the face of two cyclopentadienyl [η<small><sup>5</small></sup>-(C<small><sub>5</sub></small>H<small><sub>5</sub></small>)] ligands which lie in parallel planes. The term should not be used for analogues having rings other than cyclopentadienyl as ligands.