Plenary - Advances in Organic and Inorganic Chemistry

Molecular Electrocatalysis: Activation of Small Molecules with Transition Metal Complexes

Inke Siewert

Institut für Anorganische Chemie, Georg-August-Universität Göttingen, GER

Proton-coupled electron transfer reactions are essential for a wide range of energy conversion reactions such as water splitting, CO2 reduction, or N2 splitting. 1 In fact, electrons, holes, and protons are the energy carrier in sustainable fuel cycles. Thus, metal complexes with proton responsive ligands have been investigated as molecular catalysts in such reactions and they proved to be very beneficial as they can mediate proton and electron transfer processes. 2

We utilize imidazole, pyrazole, and phenol units as proton responsive entities in such metal complexes. Initial investigation on the thermochemistry of these metal-ligand combinations showed indeed a reasonable thermodynamic coupling of the electron and proton transfer event.3 The application of such complexes in the electrochemically-driven water splitting and CO2 reaction will be discussed.4 Furthermore, the first example of electrochemical N2 splitting forming a very stable nitride complex will be presented.5

The talk focuses on mechanistic investigation by means of electrochemical methods in order to obtain a full picture of the coupled electrochemical and chemical reactions during the transformation of the small molecules.

  1. Warren, J. J.; Mayer, J. M. Biochemistry 2015, 54, 1863.

  2. for example: Waidmann, C. R.; Miller, A. J. M.; Ng, C.-W. A.; Scheuermann, M. L.; Porter, T. R.; Tronic, T. A.; Mayer, J. M. Energy Environ. Sci. 2012, 5, 7771; Costentin, C.; Robert, M.; Savéant, J.-M.; Tard, C. Acc. Chem. Res. 2014, 47, 271; Zhang, T.; Wang, C.; Liu, S.; Wang, J.-L.; Lin, W. J. Am. Chem. Soc. 2014, 136, 273; Matheu, R.; Ertem, M. Z.; Benet-Buchholz, J.; Coronado, E.; Batista, V. S.; Sala, X.; Llobet, A. J. Am. Chem. Soc. 2015.

  3. Wilting, A.; Kügler, M.; Siewert, I. Inorg. Chem. 2016, 55, 1061; M. Wilken, C. Würtele, M. Kügler, F. Chrobak, I. Siewert, Eur. J. Inorg. Chem. 2018,  2339-2344.

  4. Siewert, I.; Gałęzowska, J. Chem. Eur. J. 2015, 21, 2780; Wilting, A.; Stolper, T.; Mata, R. A.; Siewert, I. Inorg. Chem. 2017, 56, 4176; J.-P. Du, A. Wilting, I. Siewert, Chem. Eur. J. 2019, accepted, DOI: 10.1002/chem.201806398.

  5. B. M. Lindley, R. S. van Alten, M. Finger, F. Schendzielorz, C. Würtele, A. J. M. Miller, I. Siewert, S. Schneider, J. Am. Chem. Soc. 2018, 7922–7935.