Past event

School of Chemistry Colloquium: Dr Niklas von Wolff (Université Paris Cité/CNRS)

Title: – “Sparks and Flashes: Electro- AND Photochemical Activation of Metal-Ligand Cooperative Catalysts”

The development of energy and atom efficiency processes is thought to play an important role for a sustainable chemical industry of the future. One opportunity could be the electrification of thermal processes to benefit from the inherent advantages of electrochemistry, such as safety, scalability, a cheap and traceless redox agent (electrons), and the possibility to directly control the energy input of a given reaction through the applied potential. In our group, we are interested if we use novel electrochemical and photochemical ways to activate organometallic catalysis and thus contribute to the development of energy efficient processes.
In recent years, the construction of novel C-N bonds from simple and potentially renewable feedstock (alcohols and amines) spurred interest in the community.[1,2] This is a particular challenge due to the redox labile nature of amines, making undesired amine oxidation both thermodynamically and kinetically more facile. Here, we demonstrate that our recent efforts to electrify aromatic pincer complexes,[3] known to catalyze acceptor-less dehydrogenation reactions, can be extended to formation of C-N bonds directly from alcohols and amines. We demonstrate that such catalysts are indeed robust candidates, that allow to avoid high working potentials to access the coupling of a variety of amines substrates with benzyl alcohols.[4]
Whereas electrochemistry can have many advantages, we are also interested in photochemically induced reactivity. In a case-study, we investigated the photochemical activation of a rhodium pincer complex, that is able to activate strong C-H bonds, such as in benzene. Based on our mechanistic findings, we were able to design novel photochemical conditions for the efficient carbonylation of benzene with such systems.

[1] J. Li, Y. Zhang, K. Kuruvinashetti, N. Kornienko, Nat Rev Chem 2022, 6, 303–319.
[2] J. Shao, N. Meng, Y. Wang, B. Zhang, K. Yang, C. Liu, Y. Yu, B. Zhang, Angewandte Chemie International Edition n.d., n/a, e202213009.
[3] D. Tocqueville, F. Crisanti, J. Guerrero, E. Nubret, M. Robert, D. Milstein, N. von Wolff, Chem. Sci. 2022, DOI 10.1039/D2SC04533H.
[4] S. Kasemthaveechok, N. von Wolff, 2022, DOI 10.26434/chemrxiv-2022-n306b.