Chemische Bindung und «relativistischer nephelauxetischer Effekt» in Übergangsmetallkomplexen. Diskussion von optischen Spektren und ESR-Daten von Cu(II)-Komplexen in Einkristallen

Abstract

ESR and optical investigations of Copper(II) Picolinate in several host lattices (single crystals) show clearly that the naive LCAO model (linear combination of ground state atomic Hartree-Fock orbitals) is inadequate to describe the analytical form of the singly occupied molecular orbitals in Transition Metal complexes. In order to get agreement with experiment, at least a scaling parameter for the central ion 3d-orbital part must be introduced which accounts for expansive promotion, a principle which is quite generally observed in orbitals of antibonding character as has been shown theoretically by K. Ruedenberg in 1962. It is shown that expansive promotion of d-orbitals accounts for a substantial part of the generally observed decrease of spin-orbit coupling in Transition Metal Ions in their complexes compared with their free ion (or free atom) state.