Quantum Chemical Calculations of Transition Metal Complexes

Abstract

Transition metal complexes show a wide variety of chemical reactions. To gain insight into the bonding situation of these complexes and the transition states involved in these reactions is not only crucial for understanding the underlying principles, but even more for finding new reaction pathways or optimising reaction conditions in chemical industry. Where experiments fail to obtain the needful results, modern quantum chemical approaches can be utilised to investigate chemical systems and predict their properties. This is a challenging task for computational chemists and the necessary calculations, particularly at high levels of theory, are demanding in computational resources. Our research focuses on quantum chemical calculations of transition metal compounds using ab initio methods and density functional theory. The goal of our investigations is the exact calculation of bond energies and activation barriers, which are very difficult to obtain experimentally. In the course of our investigation we found out that coupled cluster calculation at the CCSD(T) level in conjunction with quasirelativistic small-core effective core potentials and valence basis functions of DZ+P quality give very accurate results. We are studying now the strength of various transition metal ligand bonds and the reaction profiles of important transition metal compounds in order to make predictions for new experiments. Coupled cluster calculations are computationally extremely demanding and thus, the access to supercomputers is absolutely necessary for our research. Calculations of this quality make it possible for us to predict accurate data about chemical reactions and bond energies, which can be considered as true top research on a worldwide level. The following chapters give an overview about the research of our group using computational resources of the HLR Stuttgart.