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New Concepts for Designing d~(10)-M(L)_n Catalysts: d Regime, s Regime and Intrinsic Bite-Angle Flexibility

机译:设计d〜(10)-M(L)_n催化剂的新概念:d制度,s制度和固有的咬角柔性

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Our aim is to understand the electronic and steric factors that determine the activity and selectivity of transition- metal catalysts for cross-coupling reactions. To this end, we have used the activation strain model to quantum-chemically analyze the activity of catalyst complexes d~(10)-M(L)_n toward methane C-H oxidative addition. We studied the effect of varying the metal center M along the nine d~(10) metal centers of Groups 9, 10, and 11 (M=Co~-, Rh~-, Ir~-, Ni, Pd, Pt, Cu~+, Ag~+, Au~+), and, for completeness, included variation from uncoordinated to mono- to bisligated systems (n=0, 1, 2), for the ligands L=NH_3, PH_3, and CO. Three concepts emerge from our activation strain analyses: 1) biteangle flexibility, 2) d-regime catalysts, and 3) s-regime catalysts. These concepts reveal new ways of tuning a catalyst's activity. Interestingly, the flexibility of a catalyst complex, that is, its ability to adopt a bent L-M-L geometry, is shown to be decisive for its activity, not the bite angle as such. Furthermore, the effect of ligands on the catalyst's activity is totally different, sometimes even opposite, depending on the electronic regime (d or s) of the d~(10)-M(L)_n complex. Our findings therefore constitute new tools for a more rational design of catalysts.
机译:我们的目的是了解决定过渡金属催化剂交叉偶联反应活性和选择性的电子和空间因素。为此,我们使用活化应变模型对催化剂配合物d〜(10)-M(L)_n对甲烷C-H氧化加成的活性进行了量子化学分析。我们研究了沿第9、10和11组的9个d〜(10)金属中心改变金属中心M的影响(M = Co〜-,Rh〜-,Ir〜-,Ni,Pd,Pt,Cu 〜+,Ag〜+,Au〜+),并且为了完整起见,还包括配体L = NH_3,PH_3和CO从不配位到单配位到双配位的系统变化(n = 0、1、2)。我们的活化应变分析提出了一些概念:1)咬合柔性,2)d-型催化剂和3)s-型催化剂。这些概念揭示了调节催化剂活性的新方法。有趣的是,催化剂配合物的柔性,即其采用弯曲的L-M-L几何形状的能力,显示出对其活性起决定性作用,而不是其咬合角。此外,取决于d〜(10)-M(L)_n配合物的电子形式(d或s),配体对催化剂活性的影响完全不同,有时甚至相反。因此,我们的发现构成了更合理设计催化剂的新工具。

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