Zur Anwendung gemischt elektrostatisch-quantenchemischer Modelle zur Beschreibung von Metallkomplexen mit Amiden

Abstract

Three different, mixed electrostatic-quantum chemical models for the description of metal-amide complexes have been tested. Two of them contain an electrostatic approximation for the metal ion, the third intends to give a better approximation to the liquid phase, i.e. the solution, by means of an electrostatic concept taking into account further ligand molecules, but maintaining the quantum chemical treatment of the metal. The results of the calculations are discussed in connection with experimental data. The applicability of the models within certain limitations confirm the conclusion, that electrostatic and polarization effects represent the dominant interaction terms between ions and amide ligands, as assumed already on the basis of experimental data. The electrostatic-quantum chemical models allow an extension of the theoretical treatment of complexes to metal ions of higher atom number, and a remarkable improvement of the absolute values for stabilization energies and rotational barriers without significant increase in computing time.