Research Interests

We aim to understand the electronic structures and functional principles of inorganic complexes with quantum chemical methods. To closely link experiment and theory, we predict the spectroscopic, magnetic or otherwise measurable properties of transition metal complexes. We are interested in systems that are have unexpected properties, are magnetically coupled, can achieve difficult molecular transformations, or show promising catalytic activity.

The activation and splitting of the strong nitrogen-nitrogen bond in the N2 molecule is a difficult and intriguing chemical transformation that is important for the synthesis of base chemicals. Industrially, the Haber-Bosch-process is used, which relies on fossil hydrogen sources. Alternative ways to achieve nitrogen splitting with a smaller environmental impact are currently realised on lab scale using thermal, electrochemical and photochemical routes.

We use density functional theory and wave function methods to gain a better understanding of the functional principles and conditions under which nitrogen activation can be achieved with molecular complexes, with a particular focus on nitrogen photoactivation.

Water oxidation, i.e. removing electrons and protons from two water molecules and forming a dioxygen molecule, is one of the key chemical reactions toward the development of a global energy economy that relies on sunlight as the primary energy source. This reaction is also used in nature as an important step in photosynthesis.

Synthetic water oxidation catalysts often rely on expensive transition metals or are not yet commercially viable for other reasons. We use computational chemistry to identify and characterize reactive intermediates in experimentally known catalytic cycles. Our long-term goal is to design improved systems that are efficient, stable and affordable.

The oxygen reduction reaction is an important step in fuel cell chemistry. Currently, platinum-based catalysts are used in fuels cells, which is expensive and prohibits their widespread utilisation.

Together with Prof. U. I. Kramm (TU Darmstadt), we study so-called FeNC catalysts, which represent a green alternative to platinum-based catalysts. The key aspect is the combination of experimental and ocmputational Mössbauer spectroscopy, by which we can identify the atomic-scale composition of the catalytically active sites.

The electronic structures of first-row transition metal oligomers with unpaired electrons localised primarily on the metal ions are dominated by magnetic coupling. We use density functional theory and wavefunction methods to describe and analyse exchange-coupled systems.

Transition metal complexes that can accumulate several redox equivalents, i.e. electrons or holes, are quite common in catalytic processes in nature. In man-made catalytic cycles the electronic properties of such redox accumulators need to be tailored to match those of the catalytically active entity.

We use computational chemistry to understand which factors influence the overall redox potential, the potential range in which electrons are taken up or dispensed, and the total number of redox equivalents that can be stored.