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首页> 外文期刊>RSC Advances >pH-Dependent transfer hydrogenation or dihydrogen release catalyzed by a [(η6-arene)RuCl(κ2-N,N-dmobpy)]+ complex: a DFT mechanistic understanding
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pH-Dependent transfer hydrogenation or dihydrogen release catalyzed by a [(η6-arene)RuCl(κ2-N,N-dmobpy)]+ complex: a DFT mechanistic understanding

机译：由[（η6-芳烃）Rucl（κ2-n，n-Dmobpy）] +复合物催化的pH依赖性转移氢化或二氢释放物质：DFT机械理解

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摘要

The reaction mechanism of the pH-dependent transfer hydrogenation of a ketone or the dehydrogenation of formic acid catalyzed by a [(η ~(6) -arene)RuCl(κ ~(2) - N , N -dmobpy)] ~(+) complex in aqueous media has been investigated using the density functional theory (DFT) method. The TM-catalyzed TH of ketones with formic acid as the hydrogen source proceeds via two steps: the formation of a metal hydride and the transfer of the hydride to the substrate ketone. The calculated results show that ruthenium hydride formation is the rate-determining step. This proceeds via an ion-pair mechanism with an energy barrier of 14.1 kcal mol ~(?1) . Interestingly, the dihydrogen release process of formic acid and the hydride transfer process that produces alcohols are competitive under different pH environments. The investigation explores the feasibility of the two pathways under different pH environments. Under acidic conditions (pH = 4), the free energy barrier of the dihydrogen release pathway is 4.5 kcal mol ~(?1) that is higher than that of the hydride transfer pathway, suggesting that the hydride transfer pathway is more favorable than the dihydrogen release pathway. However, under strongly acidic conditions, the dihydrogen release pathway is more favorable compared to the hydride transfer pathway. In addition, the ruthenium hydride formation pathway is less favorable than the ruthenium hydroxo complex formation pathway under basic conditions.
机译：酮的pH依赖性转移氢化的反应机理或A的甲酸脱氢或α（η〜（6） - are one）Rucl（κ〜（2） - n，n -dmobpy）]〜（+ ）使用密度泛函理论（DFT）方法研究了水性介质中的络合物。用甲酸作为氢源的TM催化剂的酮通过两步进行：形成金属氢化物和氢化物的转移到基底酮。计算结果表明，氢化物形成是速率确定步骤。这通过离子对机构进行，其能量屏障为14.1kcal mol〜（α1）。有趣的是，在不同的pH环境下产生甲酸的二氢释放过程和产生醇的氢化物转移过程是竞争力的。该调查探讨了不同pH环境下两种途径的可行性。在酸性条件下（pH = 4），二氢释放途径的自由能屏障是4.5kcal mol〜（Δ1），其高于氢化物转移途径的氢化物转移途径，表明氢化物转移途径比二氢释放路线。然而，在强酸性条件下，与氢化物转移途径相比，二氢释放途径更有利。此外，在基本条件下，氢化钌形成途径比钌羟化型络合物形成途径更低。

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