Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States.
Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
J Am Chem Soc. 2017 Nov 22;139(46):16548-16555. doi: 10.1021/jacs.7b07373. Epub 2017 Nov 9.
The current understanding of ligand effects in transition metal catalysis is mostly based on the analysis of catalyst-substrate through-bond and through-space interactions, with the latter commonly considered to be repulsive in nature. The dispersion interaction between the ligand and the substrate, a ubiquitous type of attractive noncovalent interaction, is seldom accounted for in the context of transition-metal-catalyzed transformations. Herein we report a computational model to quantitatively analyze the effects of different types of catalyst-substrate interactions on reactivity. Using this model, we show that in the copper(I) hydride (CuH)-catalyzed hydroamination of unactivated olefins, the substantially enhanced reactivity of copper catalysts based on bulky bidentate phosphine ligands originates from the attractive ligand-substrate dispersion interaction. These computational findings are validated by kinetic studies across a range of hydroamination reactions using structurally diverse phosphine ligands, revealing the critical role of bulky P-aryl groups in facilitating this process.
目前对过渡金属催化中配体效应的理解主要基于对催化剂-底物的成键和非成键相互作用的分析，后者通常被认为具有排斥性。配体与底物之间普遍存在的色散相互作用是一种吸引性的非共价相互作用，但在过渡金属催化转化的背景下很少被考虑。在此，我们报告了一种计算模型，用于定量分析不同类型的催化剂-底物相互作用对反应性的影响。使用该模型，我们表明在铜 (I) 氢化物 (CuH) 催化的非活化烯烃的氢胺化反应中，基于大位阻双齿膦配体的铜催化剂具有显著增强的反应性，这源于配体-底物的吸引性色散相互作用。这些计算结果通过使用结构多样的膦配体进行一系列氢胺化反应的动力学研究得到了验证，揭示了大位阻 P-芳基在促进这一过程中的关键作用。
