A new application of molecular mechanics. Conformational calculations of transition metal π-complexes

A simplified variant of the molecular mechanical model, allowing to describe geometric features of the π-complex molecules quite well without using orbital (electron) representations is suggested. The model of the single-nuclear π-complex used is based on representation about uniform filling of a metal coordination sphere by ligands, and the achievement of the energy minimum of nonvalent interligand interaction is considered to be the criterion of uniform filling. The calculaion results of complex geometry of some transition metals (M=Zr, Hf, V, Nb, Ta, Mo) with different ligands (L) have shown that the model used permits to achieve semiquantitative correspondence of calculated and experimental angles L-M-L (divergence -5-10 deg) and to restore some fine features of the transition metal π-complex structure