Tuning Selectivity in Reductive Amination Through Orbital Symmetry Engineering of Metal‐Organic Supports

ABSTRACT Controlling selectivity in the reductive amination of carbonyls, a pivotal green route to amines, remains a long‐standing challenge within complex reaction networks. Here, we report a strategy to precisely steer product selectivity by engineering the orbital symmetry of coordinatively unsaturated metal sites (CUSs) on metal‐organic layers (MOLs) that support ruthenium nanoparticles (Ru NPs). Across diverse substrates, Zn‐based MOLs with Zn 2 (CO 2 ) 4 paddle‐wheel secondary building units (SBUs) favor primary amines, whereas their Cu‐based analogues with Cu 2 (CO 2 ) 4 SBUs solely produce Schiff bases. This divergence originates from a picoscale symmetry‐broken Cu‐O 4 geometry in the Cu 2 (CO 2 ) 4 unit, which weakens the adsorption and activation of Schiff base intermediates, thereby kinetically retarding their further ammonolysis. Our work establishes a paradigm for controlling catalytic selectivity through picoscale orbital symmetry manipulation at support metal sites.