Manganese Atom-Induced Lattice Distortion in Fe₃O₄ to Boost Selective Transfer Hydrogenation of Unsaturated Oxygenates

The development of heterogeneous catalysts and the clarification of their catalytic mechanisms are essential for the transfer of hydrogenation of oxygenated functional groups. By employing a doping and defect engineering strategy, we synthesized Fe-based spinel catalysts using a simple sol–gel method. Remarkably, such a catalyst demonstrates an ultrahigh selectivity of 98.6% in the transfer hydrogenation of cinnamaldehyde and also shows good universality in the reduction of carbonyl or nitro compounds with conjugated C═C bonds. The notable improvement in catalytic performance is attributed to the incorporation of Mn atoms, which form an inverse spinel structure and induce lattice distortion, thereby constructing more dynamic active centers. Furthermore, a catalytic paradigm based on the coadsorption of substrates at different metal sites is proposed through structure–activity relationship analysis and validated using in situ monitoring techniques. Isotopic labeling experiments have delineated the hydrogen transfer pathways, affirming that the reaction adheres to a substrate coordination mechanism. Pioneering the integration of NMR testing with theoretical calculations, we have elucidated that the Mn and Fe biactive centers facilitate a stepwise transfer hydrogenation mechanism, overcoming the constraints of single-step mechanisms in understanding the hydrogenation of nitro compounds. Our findings provide valuable insights into the design of highly selective transfer hydrogenation catalysts for oxygenated functional groups in unsaturated compounds.