Dr. Gregor Kemper & Dr. Anne-Christine Kick - Organometallic CO2 Chemistry

Vita
B.Sc. University of Konstanz (2008-2011)
M.Sc. University of Konstanz - Prof. Dr. S. Mecking (2012-2015)
Dr. rer. nat. RWTH Aachen University, Institute for Technical and Macromolecular Chemistry - Prof. Dr. Walter Leitner (2016-2020)
PostDoc RWTH Aachen University, Institute for Technical and Macromolecular Chemistry - Prof. Dr. Walter Leitner (2021-2022)
MPI CEC, Molecular Catalysis - Prof. Dr. Walter Leitner (2023)
Group leader 'Organometallic CO2 Chemistry', MPI CEC (seit 2024)

 

Publications

Full publications list | ORCID

Selected MPI CEC publications

  • Voit, G.; Jenthra, S.; Hölscher, M.; Weyhermüller, T.; Leitner, W. Reversible insertion of carbon dioxide at phosphine sulfonamido PdII–aryl complexes. Organometallics 2020, 39 (24), 4465-4473.
  • Kemper, G.; Hölscher, M.; Leitner, W. Pd (II)-catalyzed carboxylation of aromatic C─ H bonds with CO2. Science Advances 2023, 9 (5), eadf2966.
  • Singh, A.; Kemper, G.; Weyhermueller, T.; Kaeffer, N.; Leitner, W. Activated Mn‐MACHO Complexes Form Stable CO2 Adducts. Chemistry–A European Journal 2023, e202303438.
Vita
B. Sc.RWTH Aachen University (2013-2016)
M. Sc.RWTH Aachen University (2016-2019)
PhDRWTH Aachen University, Institut für Technische und Makromolekulare Chemie - Prof. Dr. Walter Leitner (2019-2023)
PostDocMPI CEC, Elektrosynthese - Prof. Dr. Siegfried Waldvogel (2023-2024)
PostDocMPI CEC, Molekulare Katalyse - Prof. Dr. Walter Leitner (2025-2026)
Gruppenleiter'Metallorganische CO2 Chemie', MPI CEC (seit 2026)
Publications

Publications

2026
A.-C. Kick, M. Schatz, C. Kahl, M. Hölscher, R. A. Eichel, J. Granwehr, N. Kaeffer, W. Leitner. Mapping proton and carbon dioxide electrocatalytic reductions at a Rh complex by in situ spectroelectrochemical NMR. Chem. Sci. 2026, 17, 1637-1646.
 

2024
A.-C. Kick, T. Weyhermüller, M. Hölscher, N. Kaeffer, W. Leitner. Understanding Ligand Effects on Bielectronic Transitions: Chemo- and Electroreduction of Rhodium Bis(Diphosphine) Complexes to Low Oxidation States. Angew. Chem. Int. Ed. 2024, 63, e202408356.

Group members

PhD students

Himani Bisht
Florian Dobreff
David Ezenarro
Zeynep Kap Dinler
Arjit Mahana
Natalia Mendoza Vallejo
Paul Resch
Angshuman Sarmah
Ilamparithy Selvakumar

Lab staff

Carsten Hindemith
Aaron Konrad Felix Kretschmer
Open positions

The Organometallic CO2 Chemistry group is always looking for interested and talented students, PhD students and PostDocs. Candidates who are enthusiastic about organometallic chemistry, would like to understand reaction mechanisms and to conduct fundamental research in a motivating environment that might contribute to applications for a more sustainable world are cordially invited to contact Gregor Gregor Kemper.

Research in the Group Organometallic CO2 Chemistry

In the “Organometallic CO2 Chemistry” team, we develop homogeneous transition metal catalysts for the utilization of carbon dioxide (CO2) in novel thermo- and electrocatalytic processes, thus converting this greenhouse gas with other non-fossil raw materials into fine and base chemicals as well as energy storage media.

Keeping up with Planck's motto, “insight must precede application”, we are particularly interested in in-depth understanding of underlying reaction mechanisms, which we establish through catalysis/electrolysis experiments, (NMR) spectroscopy, spectroelectrochemistry, cyclic voltammetry, isolation and characterization of intermediates and X-ray diffraction. This conception is supported by computational chemistry calculations (DFT), some of which are carried out in close collaboration with the “Computational Chemistry in Homogeneous Catalysis” group led by Dr. Markus Hölscher at RWTH Aachen University. We aim for using computational methods not only as an analytical tool to explain experimental observations, but also for the ab initio prediction of catalyst structures and previously unknown catalytic cycles.1

This fundamental understanding of reactions ultimately enables the development of rationally tailored catalysts to facilitate selective and atom-economical conversions of CO2 and related starting materials under mild thermal or electrochemical reaction conditions.

Fig. 1: Use of organometallic compounds in the development of new catalytic transformations of CO2.

Background: Circular economy and defossilization

In view of the climate crisis and the ongoing release of toxic and persistent chemicals into the environment, a fundamental transformation of the chemical industry and the energy sector is needed. While the latter can - at least in theory - be completely decarbonized, products for chemical applications will still largely rely on the element carbon. Therefore, a circular and holistic chemical industry, which recycles carbon-containing products at the end of their life cycle and reuses this carbon in chemical synthesis, needs to be entrenched. In search for more efficient products or alternative reaction pathways to established products, additional aspects need to be considered, such as the avoidance of toxic or persistent waste, improvement of atom economy and elimination of toxic, fossil, and conflict-causing raw materials. In this way, sustainability is understood as an integral part of product performance.2, 3

In addition to biomass feedstocks and green hydrogen, the conversion of the greenhouse gas CO2 has the potential for major contribution to the defossilization of the chemical value chain. It is a non-toxic, non-flammable, and inexpensive source of carbon that is (more than) abundant in our atmosphere and is continuously emitted on a very large scale. However, due to its properties as a very stable and unreactive molecule, suitable catalysts are required for its activation and conversion.

Reversible hydrogenation of carbonyl compounds with 3d metals

Fig. 2: The methanol tetrahedron as a representation of the mutual interconversion of different C1 building blocks through reversible hydrogenation of carbonyl compounds with dihydrogen using molecular Mn(I) complexes.

One of our main interests is the reversible hydrogenation of carbonyl compounds with molecular hydrogen. These reactions are of particular importance for the development of novel technologies using CO2 as a fundamental carbon source, as they allow direct access to carbon atoms at different reduction levels. The interconvertible C1 building blocks CO2 (+4), formic acid (+2), carbon monoxide (+2), formaldehyde (0), and methanol (-2) can either be used as hydrogen/energy storage materials or—either after isolation or in situ—in further reaction sequences to build molecular diversity. Pursuing this approach, we investigate various catalytic transformations, such as the hydrogenation of esters, aldehydes and ketones, the selective dehydrogenation of methanol, and the challenging direct hydrogenation of CO2 to methanol under mild reaction conditions.4, 5

To enable and/or improve these reactions in line with the principles green chemistry, we focus our research on molecular catalysts that replace precious metal centers by 3d metals, such as manganese, which is earth abundant and thus cheaper and exploitable at lower greenhouse gas emissions. We combine these with pincer ligands capable of metal-ligand cooperation (MLC) to activate molecules like molecular hydrogen. In addition to the targeted, partly computer-aided development of novel manganese complexes, we are interested in elucidating the underlying reaction mechanisms. A central approach here is the isolation and characterization of stable organometallic intermediates that occur in these reaction mechanisms and can significantly influence the energy barriers to be overcome.6

Organometallic electrocatalysis

In electroreductions, hydride complexes are typical key intermediates, that thermochemically form by dihydrogen activation either directly at the metal center or by MLC. An alternative approach is the electrochemical reduction of the metal centers and subsequent protonation in acid media. Through spectroelectrochemical NMR experiments (collaborative work), we already gained interesting insights into the electrochemical catalyst activation, the electrochemical formation of hydride complexes, and the electrocatalytic reduction of CO2 at rhodium phosphine complexes under operando conditions.7 Our group currently investigates the influence of various ligand parameters and MLC on the electrochemical properties of metal complexes, their activation, and hydride transfer to unsaturated moieties.8, 9

In order to avoid hydrogen evolution (HER) as a frequent but undesirable side reaction in electroreductions, we further investigate, in collaboration with Nicolas Kaeffer's group at the Laboratoire d'innovation moléculaire et applications in Strasbourg, electrocatalytic transformations on nickel bipyridine complexes that e.g. enable the selective semihydrogenation of alkynes to Z-alkenes while avoiding hydride intermediates.10

 

(1) Kemper, G.; Hölscher, M.; Leitner, W. Pd (II)-catalyzed carboxylation of aromatic C─ H bonds with CO2. Science Advances 2023, 9 (5), eadf2966.
(2) Zimmerman, J. B.; Anastas, P. T.; Erythropel, H. C.; Leitner, W. Designing for a green chemistry future. Science 2020, 367 (6476), 397-400.
(3) Artz, J.; Müller, T. E.; Thenert, K.; Kleinekorte, J.; Meys, R.; Sternberg, A.; Bardow, A.; Leitner, W. Sustainable conversion of carbon dioxide: an integrated review of catalysis and life cycle assessment. Chemical reviews 2018, 118 (2), 434-504.
(4) Kuß, D. A.; Hölscher, M.; Leitner, W. Combined Computational and Experimental Investigation on the Mechanism of CO2 Hydrogenation to Methanol with Mn-PNP-Pincer Catalysts. ACS Catalysis 2022, 12, 15310-15322.
(5) Kuß, D. A.; Hölscher, M.; Leitner, W. Hydrogenation of CO2 to Methanol with Mn‐PNP‐Pincer Complexes in the Presence of Lewis Acids: the Formate Resting State Unleashed. ChemCatChem 2021, 13 (14), 3319-3323.
(6) Singh, A.; Kemper, G.; Weyhermueller, T.; Kaeffer, N.; Leitner, W. Activated Mn‐MACHO Complexes Form Stable CO2 Adducts. Chemistry–A European Journal 2023, e202303438.
(7) Kick, A. C.; Schatz, M.; Kahl, C.; Hölscher, M.; Eichel, R. A.; Granwehr, J.; Kaeffer, N.; Leitner, W. Mapping proton and carbon dioxide electrocatalytic reductions at a Rh complex by in situ spectroelectrochemical NMR. Chemical Science 2026, 17 (3), 1637-1646.
(8) Kick, A.-C.; Weyhermüller, T.; Hölscher, M.; Kaeffer, N.; Leitner, W. Understanding Ligand Effects on Bielectronic Transitions: Chemo- and Electroreduction of Rhodium Bis(Diphosphine) Complexes to Low Oxidation States. Angewandte Chemie International Edition 2024, 63 (37), e202408356.
(9) Singh, A.; Sarmah, A.; Kick, A.-C.; Reck, P.; Weyhermüller, T.; Kemper, G.; Leitner, W.; Kaeffer, N. Molecular Mn Centers for Electrochemical C=O Reduction: Pincer Complexes and Comparative Analysis. manuscript in preparation.
(10) Durin, G.; Lee, M.-Y.; Pogany, M. A.; Weyhermüller, T.; Kaeffer, N.; Leitner, W. Hydride-Free Hydrogenation: Unraveling the Mechanism of Electrocatalytic Alkyne Semihydrogenation by Nickel–Bipyridine Complexes. Journal of the American Chemical Society 2023, 145 (31), 17103-17111.