Editing Cyclopentadienyl complex (section)

==Variations of Cp complexes==
<gallery caption="Variations of Cyclopentadienyl complexes" widths="160px" heights="100px">
File:Decamethylcobaltocene.svg|[[Decamethylcobaltocene]], a powerful reducing agent derived from "Cp*".
File:ConstrainedGeomCmpx.png|A [[Constrained geometry complex|constrained geometry organotitanium complex]]
File:Ansa-Metallocene.svg|An [[ansa-metallocene]]
File:Cp"2Fe2N2.png|[[Bulky Cp ligand]] as found in (<sup>''t''</sup>Bu<sub>3</sub>C<sub>5</sub>H<sub>2</sub>)<sub>2</sub>Fe<sub>2</sub>N<sub>2</sub>
</gallery>

===Ansa Cp ligands===
{{main|Ansa-metallocene}}
A pair of cyclopentadienyl ligands can be covalently linked giving rise to so-call ansa metallocenes.  The angle between the two Cp rings is fixed.  Rotation of the rings about the metal-centroid axis is stopped as well.  A related class of derivatives give rise to the [[constrained geometry complex]]es.  In these cases, a Cp ligand as linked to a non-Cp ligand.  Such complexes have been commercialized for the production of polypropylene.

===Bulky Cp ligands===
{{main|Bulky cyclopentadienyl ligands}}
[[Pentamethylcyclopentadiene]] gives rise to pentamethylcyclopentadienyl (Cp*) complexes.  These ligands are more basic and more lipophilic.  Replacing methyl groups with larger substituents results in cyclopentadienes that are so encumbered that pentaalkyl derivatives are no longer possible. Well-studied ligands of this type include C<sub>5</sub>R<sub>4</sub>H<sup>−</sup> (R = iso-Pr) and 1,2,4-C<sub>5</sub>R<sub>3</sub>H<sub>2</sub><sup>−</sup> (R = ''tert''-Bu).

===Constrained geometry complexes===
{{main|constrained geometry complex}}
Constrained geometry complexes are related to ansa-metallocenes except that one ligand is not Cp-related.