A High-Valent Ru-PCP Pincer Catalyst for Hydrogenation of Carbonyl and Carboxyl Compounds under Molecular Hydrogen

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 Ru-IV 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.

Automated summary

Traditionally, low-valent metals dominate the field of catalytic hydrogenation, but high-valent metals can also achieve catalytic hydrogenation through heterolytic bond activation, with better efficiency than low-valent metals. The Ru-IV catalyst with a bifunctional PCP pincer ligand can efficiently catalyze the hydrogenation of aldehydes and carboxylic compounds under molecular hydrogen, even at room temperature.