Stacking interactions of the methylated cyclopentadienyl ligands in the crystal structures of transition metal complexes.

In the crystal structures of methylated cyclopentadienyl (Cp) complexes (MeCp, Me4Cp and Me5Cp) deposited in the Cambridge Structural Database, certain orientation types of stacked contacts can be noted as the most frequent. These orientation preferences can be well explained by the matching of oppositely charged regions of electrostatic potential. Parallel displaced stacking, large offset stacking and C-H...π interactions are the dominant interaction types that are responsible for the arrangement in the crystal structures of stacked methylated Cp complexes.