A Molecular Mechanics (MM3(96)) Force Field for Metal−Amide Complexes

A molecular mechanics (MM3(96)) force field is reported for modeling metal complexes of amides in which the amide is coordinated through oxygen. This model uses a “points-on-a-sphere” approach which involves the parametrization of the M−O stretch, the M−O C bend, and the M−O C−X (X = C, H, N) torsion interactions. Relationships between force field parameters and metal ion properties (charge, ionic radius, and electronegativity) are presented that allow the application of this model to a wide range of metal ions. The model satisfactorily reproduces the structures of over fifty amide complexes with the alkaline earths, transition metals, lanthanides, and actinides.