Defect-Engineered Ruthenium MOFs as Versatile Heterogeneous Hydrogenation Catalysts

Ruthenium MOF [Ru₃(BTC)₂Y_y] ⋅ G_g (BTC=benzene-1,3,5-tricarboxylate; Y=counter ions=Cl⁻, OH⁻, OAc⁻; G=guest molecules=HOAc, H₂O) is modified via a mixed-linker approach, using mixtures of BTC and pyridine-3,5-dicarboxylate (PYDC) linkers, triggering structural defects at the distinct Ru₂ paddlewheel (PW) nodes. This defect-engineering leads to enhanced catalytic properties due to the formation of partially reduced Ru₂-nodes. Application of a hydrogen pre-treatment protocol to the Ru−MOFs, leads to a further boost in catalytic activity. We study the benefits of (1) defect engineering and (2) hydrogen pre-treatment on the catalytic activity of Ru−MOFs in the Meerwein-Ponndorf-Verley reaction and the isomerization of allylic alcohols to saturated ketones. Simple solvent washing could not avoid catalyst deactivation during recycling for the latter reaction, while hydrogen treatment prior to each catalytic run proved to facilitate materials recyclability with constant activity over five runs.