Atomistic simulations of transition metal catalyzed reactions using specialized force fields and quantum mechanical methods

摘要

In this thesis, we utilized current computational methods for exploring molecular architectures and dynamical properties of metal-catalyzed reactions. The importance of transition metals (TM) in catalysis was our motivation to work on the development of new empirical force fields and their applications.udTM specialized force fields provide the possibility to characterize complex geometries and relate them to their reactivity. Therefore, we parametrized the VALBOND TRANS force field by refining non-bonded parameters for a large test set of octahedral iridium(III) compounds. The optimized force field allowed a successful ranking of lowest-energy diastereomers and the performance of subsequent molecular dynamic (MD) simulations. Inspired by the natural process of the photosynthesis, Ir-catalysts are also relevant for the light-induced artifical oxidation of water leading to the synthesis of dioxygen. Using parameterized force fields, we studied the role of half-sandwich iridium complexes in different proposed reaction mechanisms. The applied force fields could help to understand catalytic cycles and to establish a basis to guide experimental screenings of new effective catalysts. TM complexes are also key components in harvesting solar energy which encouraged us to investigate the function of relevant compounds such as ruthenium-tris-(2,2'-bipyridine). Its electronic excitation led to a non-equilibrium system in which excess energy was redistributed to the surrounding solvent. The determined energy transfer to the solvent and the vibrational signatures of the surrounding water supplied an explanation for experimental findings.ud