The Chemical Entities of Biological Interest (ChEBI) ontology is downloaded weekly from EMBL-EBI at http://www.ebi.ac.uk/chebi/. The data is made available under the Creative Commons License (CC BY 3.0, http://creativecommons.org/licenses/by/3.0/). For more information see: Degtyarenko et al. (2008) ChEBI: a database and ontology for chemical entities of biological interest. Nucleic Acids Res. 36, D344–D350.
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 [eta(5)-(C5H5)] ligands which lie in parallel planes. The term should not be used for analogues having rings other than cyclopentadienyl as ligands.