title: Low- and high-spin iron (II) complexes studied by effective crystal field method combined with molecular mechanics.
abstract: A computational method targeted to Werner-type complexes is developed on the basis of quantum mechanical effective Hamiltonian crystal field (EHCF) methodology (previously proposed for describing electronic structure of transition metal complexes) combined with the Gillespie-Kepert version of molecular mechanics (MM). It is a special version of the hybrid quantum/MM approach. The MM part is responsible for representing the whole molecule, including ligand atoms and metal ion coordination sphere, but leaving out the effects of the d-shell. The quantum mechanical EHCF part is limited to the metal ion d-shell. The method reproduces with reasonable accuracy geometry and spin states of the Fe(II) complexes with monodentate and polydentate aromatic ligands with nitrogen donor atoms. In this setting a single set of MM parameters set is shown to be sufficient for handling all spin states of the complexes under consideration.
authors.affiliation: L. Y. Karpov Institute of Physical Chemistry, Vorontsovo pole 10, Moscow 105064, Russia.
authors.forename: M B
authors.initials: MB
authors.lastname: Darkhovskii
authors.forename: I V
authors.initials: IV
authors.lastname: Pletnev
authors.forename: A L
authors.initials: AL
authors.lastname: Tchougréeff