Sb-Enabled Dimensional Reprogramming of Palladium Nanoclusters for Enhanced Catalysis

Strong and repetitive Pd-S interactions stabilize planar PdS₄ 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 [Pd₁₃Sb₂(PPh₃)₂(S-Adm)₁₀] (denoted as Pd₁₃Sb₂) 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 Pd₁₃Sb₂ catalyst exhibited excellent catalytic performance. Density functional theory calculations indicate that the synergistic Pd─Sb dual-site architecture not only facilitates H₂ 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.