Author:
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Vorobyeva, Evgeniya; Fako, Edvin; Chen, Zupeng; Collins, Sean M.; Johnstone, Duncan; Midgley, Paul A.; Hauert, Roland; Safonova, Olga V.; Vilé, Gianvito; López, Núria; Mitchell, Sharon; Pérez-Ramírez, Javier
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Abstract:
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Controlling the structure sensitivity of catalyzed
reactions over metals is central to developing atom-efficient
chemical processes. Approaching the minimum ensemble size,
the properties enter a non-scalable regime in which each atom
counts. Almost all trends in this ultra-small frontier derive from
surface science approaches using model systems, because of
both synthetic and analytical challenges. Exploiting the unique
coordination chemistry of carbon nitride, we discriminate
through experiments and simulations the interplay between the
geometry, electronic structure, and reactivity of palladium
atoms, dimers, and trimers. Catalytic tests evidence applicationdependent
requirements of the active ensemble. In the semihydrogenation
of alkynes, the nuclearity primarily impacts
activity, whereas the selectivity and stability are affected in
Suzuki coupling. This powerful approach will provide practical
insights into the design of heterogeneous catalysts
comprising well-defined numbers of atoms. |