Molecular mechanics of coordination compounds: force field based on Gillespie-Kepert model

I.V. Pletnev, V.L. Melnikov

Russ. J. Coord. Chem., v.23 (3), in press (1997); Proceedings of XVIII Tchugaev Conference on the Chemistry of Coordination Compounds, Moscow, Nauka, 1996, p.88

ABSTRACT. Conventional molecular mechanics (MM) is poorly applicable to coordination compounds with deformed coordination polyhedra. To overcome this drawback, we combined MM and Gillespie-Kepert semi-quantitative "bond repulsion" model. The term corresponding to bond repulsion is added to MM potential functions suite. We established a new force field parameters for high-spin Ni(II) and low/high-spin Fe(II) complexes with amino- and pyridyl-containing ligands. Calculated geometry for more than 20 complexes of Ni(II) and Fe(II) reproduces experimental structural data with high accuracy. The typical root-mean-square deviation calculations - experiment (X-ray) is 0.02 A in bond lengths, 2 deg in bond angles and 4 deg in torsion angles. We used the established force field in various applications, in particular, for the investigation of size-match selectivity of macrocycles. Another application is to the stereochemistry of metal complexes of N,N',N''-(2-pyridylmethyl)-1,4,7-triazacyclononane; herein, the switch between trigonal prismatic and octahedral coordination upon the change of central ion's size was successfully predicted.

Laboratory of Preconcentration