Journal article

Authors list: Zhong, Qg; Jung, J; Kohrs, D; Kaczmarek, LA; Ebeling, D; Mollenhauer, D; Wegner, HA; Schirmeisen, A

Publication year: 2024

Pages: 1849-1859

Journal: Journal of the American Chemical Society

Volume number: 146

Issue number: 3

ISSN: 0002-7863

eISSN: 1520-5126

DOI Link: https://doi.org/10.1021/jacs.3c05233

Publisher: American Chemical Society

Abstract: 
On-surface synthesis has proven to be a powerful approach for fabricating various low-dimensional covalent nanostructures with atomic precision that could be challenging for conventional solution chemistry. Dehydrogenative C-aryl-C(aryl )coupling is one of the most popular on-surface reactions, of which the mechanisms, however, have not been well understood due to the lack of microscopic insights into the intermediates that are fleetingly existing under harsh reaction conditions. Here, we bypass the most energy-demanding initiation step to generate and capture some of the intermediates at room temperature (RT) via the cyclodehydrobromination of 1-bromo-8-phenylnaphthalene on a Cu(111) surface. Bond-level scanning probe imaging and manipulation in combination with DFT calculations allow for the identification of chemisorbed radicals, cyclized intermediates, and dehydrogenated products. These intermediates correspond to three main reaction steps, namely, debromination, cyclization (radical addition), and H elimination. H elimination is the rate-determining step as evidenced by the predominant cyclized intermediates. Furthermore, we reveal a long-overlooked pathway of dehydrogenation, namely, atomic hydrogen-catalyzed H shift and elimination, based on the observation of intermediates for H shift and superhydrogenation and the proof of a self-amplifying effect of the reaction. This pathway is further corroborated by comprehensive theoretical analysis on the reaction thermodynamics and kinetics.

Harvard Citation style: Zhong, Q., Jung, J., Kohrs, D., Kaczmarek, L., Ebeling, D., Mollenhauer, D., et al. (2024) Deciphering the Mechanism of On-Surface Dehydrogenative C-C Coupling Reactions, Journal of the American Chemical Society, 146(3), pp. 1849-1859. https://doi.org/10.1021/jacs.3c05233

APA Citation style: Zhong, Q., Jung, J., Kohrs, D., Kaczmarek, L., Ebeling, D., Mollenhauer, D., Wegner, H., & Schirmeisen, A. (2024). Deciphering the Mechanism of On-Surface Dehydrogenative C-C Coupling Reactions. Journal of the American Chemical Society. 146(3), 1849-1859. https://doi.org/10.1021/jacs.3c05233