Low-valent metals traditionally dominate the domain of catalytic hydrogenation. However, metal-ligand cooperating (MLC) catalytic systems, operating through heterolytic H−H bond splitting by a Lewis acidic metal and a basic ligand site, do not require an electron-rich metal. On the contrary, high-valent metals that induce weaker back donation facilitate heterolytic bond activation. Here we report, for the first time, the efficient hydrogenation of carbonyl and carboxyl compounds under molecular hydrogen catalyzed by a structurally well-defined RuIV catalyst bearing a bifunctional PCP pincer ligand. The catalyst exhibits reactivity toward molecular hydrogen superior to that of the low-valent analog and allows hydrogen activation even at room temperature.
Bibliographical noteFunding Information:
We wish to thank Drs. Shmuel Cohen and Benny Boguslavsky for solving the X‐ray structures (CCDC 2172499 and CCDC 2172500). and Dr. Amani Zoabi for conducting HRMS experiments. This research was supported by German‐Israeli Foundation for Research and Development (GIF) grant no. I‐1508‐302.5/2019 and by Israel Science Foundation (ISF) grant no. 370/20. D.G. thanks the Esther K. and M. Mark Watkins Chair for Synthetic Organic Chemistry, and S.M. thanks the Neubauer Family Foundation for generous financial support.
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- cooperative catalysis
- high-valent ruthenium
- pincer complexes