Dynamically Bifurcating Hydride Transfer Mechanism and Origin of Inverse Isotope Effect for Heterodinuclear AgRu-Catalyzed Alkyne Semihydrogenation
Dynamically Bifurcating Hydride Transfer Mechanism and Origin of Inverse Isotope Effect for Heterodinuclear AgRu-Catalyzed Alkyne Semihydrogenation
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DOI：
10.1021/acscatal.8b04130
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发表时间：
2019-03-01
期刊：
影响因子：
12.9
通讯作者：
Ess, Daniel H.
中科院分区：
文献类型：
--
作者：
Zhang, Ying;Karunananda, Malkanthi K.;Ess, Daniel H.
采用密度泛函理论和实验分析了agru催化炔半氢化反应的机理和异双核协同效应。结果表明：(1)agru催化的二苯基乙炔加氢反应通过离子Ag-H氢化物转移过渡态和后过渡态的分节，初步形成顺式二苯乙烯和反式二苯乙烯的动力学混合物，并通过准经典直接动力学模拟进行了验证。(2)氢化反应表现出意想不到的逆动力学同位素效应（KIE < 1），这是由异核H-2/D-2活化的逆平衡同位素效应（EIE）引起的。(3) Ag-Ru异质双核协同效应对H-2活化和乙烯基银质子裂解反应都至关重要。(4)速率研究和计算分析表明，给电子基团加速了催化反应。
The mechanism and heterodinuclear cooperative effects for AgRu-catalyzed alkyne semihydrogenation were analyzed with density-functional theory (DFT) and experiment. This combined effort revealed the following: (1) AgRu-catalyzed diphenylacetylene hydrogenation initially gives a kinetic mixture of cis-stilbene and trans-stilbene by an ionic Ag-H hydride transfer transition state and post-transition state bifurcation, which was identified by quasiclassical direct dynamics simulations. (2) The hydrogenation reaction exhibits an unexpected inverse kinetic isotope effect (KIE < 1) resulting from an inverse equilibrium isotope effect (EIE) for heterodinuclear H-2/D-2 activation. (3) The Ag-Ru heterodinuclear cooperative effective is critical for both H-2 activation and vinylsilver protonolysis reaction steps. (4) Rate studies and computational analysis show that electron-donating groups accelerate catalysis.