Sb‐Enabled Dimensional Reprogramming of Palladium Nanoclusters for Enhanced Catalysis

Strong and repetitive Pd–S interactions stabilize planar PdS 4 motifs, confining atomic growth and suppressing the formation of three‐dimensional (3D) Pd frameworks. Here, we show that anti‐galvanic incorporation of antimony (Sb), a p‐block congener of phosphorus, selectively perturbs planar Pd─S coordination while preserving Pd─Pd connectivity. Sb acts as a dimensional regulator that enables the formation of stable, 3D Pd─Sb nanoclusters with atomic precision, as exemplified by the successful synthesis of the [Pd 13 Sb 2 (PPh 3 ) 2 (S‐Adm) 10 ] (denoted as Pd 13 Sb 2 ) nanocluster. Single‐crystal X‐ray diffraction (SCXRD) analysis unveiled a unique 3D metal kernel, a structural feature not previously reported in thiolated Pd nanoclusters. When applied to the semihydrogenation of phenylacetylene, the Pd 13 Sb 2 catalyst exhibited excellent catalytic performance. Density functional theory calculations indicate that the synergistic Pd─Sb dual‐site architecture not only facilitates H 2 activation but also optimizes the binding energy of intermediates, ensuring preferential styrene desorption and thus suppressing over‐hydrogenation. These results establish Sb‐enabled dimensional control to overcome intrinsic structural limitations in palladium nanoclusters and to unlock their catalytic potentials.