MOLECULAR MECHANICS FORCE-FIELDS FOR CYCLOPENTADIENYL COMPLEXES

A self-consistent molecular mechanics force field is developed for the reproduction of structures and energy differences of bis-cyclopentadienyl (Cp) complexes. The method is used to identify the forces which control Cp ring rotations, the conformations of substituted Cp complexes, and provides an explanation for the existence of bent metallocenes of the alkaline earth and lanthanide metals and possibly for the bent structures of the divalent silicon group. The method provides an accurate method of reproducing structures and can incorporate the structural effects caused by crystal packing forces.