Molecular mechanics modeling of organic backbone of metal-free and coordinated ligands

Abstract

A new molecular mechanics force field has been developed that takes into account the fact that, upon coordination to a transition metal ion, the redistribution of electron density leads to small but significant structural changes in the organic backbone of the ligand. Structural studies indicate that the perturbation by coordination to a metal ion extends to the α-carbon atom of the donor, the perturbation is roughly independent of the metal center for M2+ and M3+ and negligible for M+, and the perturbation of the Cα(SINGLE BOND)Cα′ bond is roughly independent of the donor atom. New parameter sets for oxalates, imidazoles, and pyrazoles are also presented. The refined parameters have been validated with a large number of monodentate, multidentate, and macrocyclic ligands. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 512–523, 1998