Anion-π interactions in five-membered rings:: a combined crystallographic and ab initio study

We have carried out searches on the Cambridge Structural Database in order to find anion-pi contacts in five-membered aromatic rings. The results indicate that anion-pi interactions are possible between anions and the cyclopentadienyl ligand in eta(5)-transition metal complexes. Ab initio calculations confirm the suitability of the interaction. (C) 2003 Elsevier B.V. All rights reserved.