The exsolution method has garnered significant attention owing to its high efficacy in developing highly efficient and stable metal nanocatalysts.Herein,a versatile exsolution approach is developed to embed size-tunab...The exsolution method has garnered significant attention owing to its high efficacy in developing highly efficient and stable metal nanocatalysts.Herein,a versatile exsolution approach is developed to embed size-tunable metal nanocatalysts within a conductive metal pnictogenide matrix.The gas-phase reaction of Ru-substituted Ni-Fe-layered-double-hydroxide(Ni_(2)Fe_(1-x)Ru_(x)-LDH)with pnictogenation reagents leads to the exsolution of Ru metal nanocatalysts and a phase transformation into metal pnictogenide.The variation in reactivity of pnictogenation reagents allows for control over the size of the exsolved metal nanocatalysts(i.e.,nanoclusters for nitridation and single atoms for phosphidation),underscoring the effectiveness of the pnictogenation-driven exsolution strategy in stabilizing size-tunable metal nanocatalysts.The Ru-exsolved nickel-iron nitride/phosphide demonstrates outstanding electrocatalyst activity for the hydrogen evolution reaction,exhibiting a smaller overpotential and higher stability than Ru-deposited homologs.The high efficacy of pnictogenation-assisted exsolution in optimizing the performance and stability of Ru metal nanocatalysts is ascribed to the efficient interfacial electronic interaction between Ru metals and nitride/phosphide ions assisted by the inner sphere mechanism.In situ spectroscopic analyses highlight that exsolved Ru single atoms facilitate more efficient electron transfer to the reactants than the exsolved Ru nanoclusters,which is primarily responsible for the superior impact of the phosphidation-driven exsolution approach.展开更多
Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis...Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis of linear‐selective products has rarely been reported.The simultaneous control of regio‐,E/Z‐and enantioselectivities constitutes a major challenge and inhibits the advancement of this chemistry.Herein,we present a palladium‐catalyzed AAA of vinyl benzoxazinanones withα‐thiocyanato ketones,affording various chiral thiocyanates characterized with high linear‐,E‐and stereoselectivities.The reaction has a broad substrate scope and the chiral thiocyanates can be transformed to useful heterocycles.Experimental and computational studies suggest an inner‐sphere mechanism for AAA process,which results from the acidic and coordination effect of the nucleophilic substrates with palladium catalyst.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(RS-2023-00208355,RS-2024-00439825,and 2022M3H4A408610313)supported by the Global Science Research Center Program(RS-2024-00411134)+1 种基金funded by the National Research Foundation of KoreaThe experiments at PAL were supported in part by MOST and POSTECH。
文摘The exsolution method has garnered significant attention owing to its high efficacy in developing highly efficient and stable metal nanocatalysts.Herein,a versatile exsolution approach is developed to embed size-tunable metal nanocatalysts within a conductive metal pnictogenide matrix.The gas-phase reaction of Ru-substituted Ni-Fe-layered-double-hydroxide(Ni_(2)Fe_(1-x)Ru_(x)-LDH)with pnictogenation reagents leads to the exsolution of Ru metal nanocatalysts and a phase transformation into metal pnictogenide.The variation in reactivity of pnictogenation reagents allows for control over the size of the exsolved metal nanocatalysts(i.e.,nanoclusters for nitridation and single atoms for phosphidation),underscoring the effectiveness of the pnictogenation-driven exsolution strategy in stabilizing size-tunable metal nanocatalysts.The Ru-exsolved nickel-iron nitride/phosphide demonstrates outstanding electrocatalyst activity for the hydrogen evolution reaction,exhibiting a smaller overpotential and higher stability than Ru-deposited homologs.The high efficacy of pnictogenation-assisted exsolution in optimizing the performance and stability of Ru metal nanocatalysts is ascribed to the efficient interfacial electronic interaction between Ru metals and nitride/phosphide ions assisted by the inner sphere mechanism.In situ spectroscopic analyses highlight that exsolved Ru single atoms facilitate more efficient electron transfer to the reactants than the exsolved Ru nanoclusters,which is primarily responsible for the superior impact of the phosphidation-driven exsolution approach.
文摘Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis of linear‐selective products has rarely been reported.The simultaneous control of regio‐,E/Z‐and enantioselectivities constitutes a major challenge and inhibits the advancement of this chemistry.Herein,we present a palladium‐catalyzed AAA of vinyl benzoxazinanones withα‐thiocyanato ketones,affording various chiral thiocyanates characterized with high linear‐,E‐and stereoselectivities.The reaction has a broad substrate scope and the chiral thiocyanates can be transformed to useful heterocycles.Experimental and computational studies suggest an inner‐sphere mechanism for AAA process,which results from the acidic and coordination effect of the nucleophilic substrates with palladium catalyst.
