Quantifying ligand effects in high-oxidation-state metal catalysis
Quantifying ligand effects in high-oxidation-state metal catalysis
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DOI：
10.1038/nchem.2843
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发表时间：
2017-09-01
期刊：
影响因子：
21.8
通讯作者：
Odom, Aaron L.
中科院分区：
文献类型：
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作者：
Billow, Brennan S.;McDaniel, Tanner J.;Odom, Aaron L.
钛（IV）等高价金属的催化作用通过烯烃聚合等反应影响着我们的日常生活。在任何催化中，优化不仅涉及金属的仔细选择，还涉及辅助配体。由于这些选择会显著影响系统的电子结构，进而影响催化剂性能，因此需要新的催化剂开发工具。理解辅助配体效应可以说是催化剂优化的最关键方面之一，虽然膦的参数已经在低价体系中使用了几十年，但高价金属不存在类似的体系。一个新的电子参数配体捐赠，来自实验的高价铬物种，现在可用。在这里，我们表明，新的参数使辅助配体的催化速率的影响，在某些情况下，甚至提供机械信息的定量测定。以这种方式分析反应可用于设计更好的催化剂结构，并为在大量高价过程中使用这些参数铺平道路。
Catalysis by high-valent metals such as titanium(IV) impacts our lives daily through reactions like olefin polymerization. In any catalysis, optimization involves a careful choice of not just the metal but also the ancillary ligands. Because these choices dramatically impact the electronic structure of the system and, in turn, catalyst performance, new tools for catalyst development are needed. Understanding ancillary ligand effects is arguably one of the most critical aspects of catalyst optimization and, while parameters for phosphines have been used for decades with low-valent systems, a comparable system does not exist for high-valent metals. A new electronic parameter for ligand donation, derived from experiments on a high-valent chromium species, is now available. Here, we show that the new parameters enable quantitative determination of ancillary ligand effects on catalysis rate and, in some cases, even provide mechanistic information. Analysing reactions in this way can be used to design better catalyst architectures and paves the way for the use of such parameters in a host of high-valent processes.