In a recent publication in the journal ACS Catalysis, scientists from the Department of Molecular Catalysis (lead by Prof. Walter Leitner) and from the Max-Planck-Institut für Kohlenforschung were able to shed light on how ruthenium-based molecular catalysts react with CO2 to make useful chemicals, such as formic acid. This type of complexes plays a particularly important role in the synthesis of a wide range of products obtained through hydrogenation reactions. Selective hydrogenation reactions are crucial in our quest towards sustainable chemical conversion, especially when considering CO2 as a substrate.
Jun.-Prof. Deven P. Estes (previously postdoc in the Bordet Group, now at the University of Stuttgart), Dr. Markus Leutzsch (NMR Department at the MPI KOFO), Lukas Schubert, Dr. Alexis Bordet (Multifunctional Catalytic Systems), and Prof. Leitner synthesized a series of Ruthenium polyhydride complexes with varying electronic properties in order to observe the effect of ligand choice on both the catalytic activity and the rate and thermodynamics of the CO2 insertion. Their findings showed that mild electron donating ligands give the highest catalytic activity and that CO2 insertion is too fast to play a role in the catalytic rate. The relationship between the electronic properties of the ligand and the turnover frequency is most likely a result of making the dissociation of formic acid from the catalyst easier by adding electron density from the phosphine donors.
Original Article: Estes, D.P., Leutzsch, M., Schubert, L., Bordet, A., Leitner, W. (2020). The Effect of Ligand Electronics on the Reversible Catalytic Hydrogenation of CO2 to Formic Acid using Ruthenium Polyhydride Complexes: A Thermodynamic and Kinetic Study, ACS Catalysis 10, 2990-2998. https://doi.org/10.1021/acscatal.0c00404