Programming Iron Nuclearity and Coordination for Hydride-Mediated Nitroarene Reduction.

Multielectron catalytic reactions intrinsically rely on cooperative metal centers, yet constructing few-atom cluster catalysts (FACCs) with controlled nuclearity, metal-metal connectivity, and electronic structure remains a fundamental challenge. Here, we show that atomically defined iron-oxo clusters can serve as structure-encoded precursors to generate supported Fe ensembles on N-doped carbon (NC), enabling systematic construction of active sites spanning isolated atoms to size-defined multinuclear clusters. During ligand removal and interfacial reconstruction, the molecular structural information is selectively inherited, giving rise to correlated evolution of Fe valence, Fe─Fe coordination and distance, and Fe─N anchoring interactions. Using hydrazine-mediated nitroarene reduction as a model multielectron reaction, we uncover a pronounced nuclearity-dependent transition in the reaction pathway, with optimal activity at intermediate nuclearity (Fe6─NC), attributable to precursor-dependent Fe─Fe cooperation and Fe─N interfacial coupling that stabilize surface hydride species. These findings provide a general basis for translating metal─oxo clusters into functional heterogeneous catalysts.