Molecular mechanical calculations of the molecular structure of eight-coordinate europium complexes

Abstract

Molecular mechanics methods were applied to the determination of the structure of eight-coordinate europium complexes: tris(acetylacetonato)Eu(III) trihydrate, tris(acetylacetonato) (1,10-phenanthroline)Eu(III), and tetrakis(benzoylacetonato)Eu(III). Optimization of MM2 force-field parameters and improvement of the calculation method were carried out using models of the complexes based on X-ray structural investigations. Steric ligandligand interactions in the first coordination sphere were treated as dominant for the lanthanide complexes. The major contributions to the energy are those of nonbonded 1,3-interactions between the atoms directly bound to the europium atom. The results of the calculations agree well with the crystal structures of the mentioned complexes.