[Cp*2Sm(THF)2] |
[Cp*2Eu] |
| The Cp*-Sm-Cp* angle in this solvated complex is 136.7° | The Cp*-Eu-Cp* angle in this solvent free complex is 140° - very close to that of the solvated analogue. |
The bending in these bis-cyclopentadienyl complexes is not due to simple crystal packing effects. It has been proposed that the polarisation resulting from bending results in favourable dipole-dipole interactions in the solid state. This only occurs for large metal ions e.g. Cp2Ca adopts the 'bent metallocene' structure whereas Cp2Mg does not.