THE MOLECULAR MECHANIC APPROACH TO COORDINATION-COMPOUNDS - FORCE-FIELD IN THE GILLESPIE-KEPERT MODEL

The set of parameters for calculating the geometry of coordination com pounds is suggested on the basis of the molecular mechanic approach co mplemented by the Gillespie-Kepert model. The high accuracy of the cal culations is demonstrated by the examples of 23 nickel(II) (high-spin state) and iron(II) (high- and low-spin states) complexes with pyridyl - and amine-containing reagents, including the compounds having severe ly distorted coordination geometry. The typical root-mean-square devia tions from the experiment (X-ray diffraction) do not exceed 0.02 Angst rom for the bond lengths, 2 degrees for the bond angles, and 5 degrees for the torsional angles. The calculations within the suggested appro ach are used for studying the selectivity of the macrocyclic reagents to the size of the metal ion and for describing the trigonal twisting in the coordination complexes.