What is Transition metal indenyl complex?

In organometallic chemistry, a transition metal indenyl complex is a coordination compound that contains one or more indenyl ligands. The indenyl ligand is formally the anion derived from deprotonation of indene. The η-indenyl ligand is related to the ηcyclopentadienyl anion , thus indenyl analogues of many cyclopentadienyl complexes are known. Indenyl ligands lack the 5-fold symmetry of Cp, so they exhibit more complicated geometries. Furthermore, some indenyl complexes also exist with only η-bonding mode. The η- and η-bonding modes sometimes interconvert.