An Initiation Kinetics Prediction Model Enables Rational Design of Ruthenium Olefin Metathesis Catalysts Bearing Modified Chelating Benzylidenes
An Initiation Kinetics Prediction Model Enables Rational Design of Ruthenium Olefin Metathesis Catalysts Bearing Modified Chelating Benzylidenes
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DOI：
10.1021/acscatal.8b00843
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发表时间：
2018-05-01
期刊：
影响因子：
12.9
通讯作者：
Grubbs, Robert H.
中科院分区：
文献类型：
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作者：
Luo, Shao-Xiong;Engle, Keary M.;Grubbs, Robert H.
具有所需引发速率的第二代钌烯烃复分解催化剂的合理设计可以通过依赖于单个热力学参数的计算模型来实现。使用一个计算模型，没有假设的具体引发机制，引发动力学的第二代钌烯烃复分解催化剂的光谱承载改性螯合邻烷氧基亚苄基在这项工作中预测。通过一系列钌烯烃复分解催化剂的合成，以及紫外可见光动力学、核磁共振（NMR）和X射线晶体学结构表征等手段对催化剂引发速率的研究，验证了计算模型的有效性。包括在这一系列的催化剂是13个催化剂携带的烷氧基与不同的空间体积上的螯合亚苄基，从乙氧基到二环己基甲氧基。实验观察到的引发动力学的合成催化剂是在良好的计算预测。值得注意的是，二环己基甲氧基催化剂的快速引发速率被成功地预测的模型，该复合物被认为是最快的引发Hoveyda-Grubbs型催化剂报道的日期。预测模型与其他催化剂家族，包括那些轴承替代N-杂环卡宾（NHC）配体或二取代烷氧基亚苄基的兼容性，也进行了检查。
Rational design of second-generation ruthenium olefin metathesis catalysts with desired initiation rates can be enabled by a computational model that is dependent on a single thermodynamic parameter. Using a computational model with no assumption about the specific initiation mechanism, the initiation kinetics of a spectrum of second generation ruthenium olefin metathesis catalysts bearing modified chelating ortho-alkoxy benzylidenes were predicted in this work. Experimental tests of the validity of the computational model were achieved by the synthesis of a series of ruthenium olefin metathesis catalysts and investigation of initiation rates by ultraviolet visible light (UV-vis) kinetics, nuclear magnetic resonance (NMR) spectroscopy, structural characterization by X-ray crystallography. Included in this series of catalysts were 13 catalysts bearing alkoxy groups with varied steric bulk on the chelating benzylidene, ranging from ethoxy to dicyclohexylmethoxy groups. The experimentally observed initiation kinetics of the synthesized catalysts were in good accordance with computational predictions. Notably, the fast initiation rate of the dicyclohexylmethoxy catalyst was successfully predicted by the model, and this complex is believed to be among the fastest initiating Hoveyda-Grubbs-type catalysts reported to date. The compatibility of the predictive model with other catalyst families, including those bearing alternative N-heterocyclic carbene (NHC) ligands or disubstituted alkoxy benzylidenes, was also examined.