Cp3La |
Cp3Sm |
Cp3Lu |
| large La3+ ion requires high c.n. therefore each La3+ is bonded to 3xeta-5 Cp ligands and 1xeta-2 Cp ligand | slightly smaller Sm3+ ion can accommodate just 3xeta-5 Cp ligands | Lu3+ is too small to accommodate 3xeta-5 Cp ligands therefore forms a polymer with 2xeta-5 and 2 bridging Cp ligands |