The Importance of Metal–Ligand Cooperativity in the Phosphorus–Nitrogen PN3P Platform: A Computational Study on Mn-Catalyzed Pyrrole Synthesis,Organometallics

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The Importance of Metal–Ligand Cooperativity in the Phosphorus–Nitrogen PN3P Platform: A Computational Study on Mn-Catalyzed Pyrrole Synthesis
Organometallics ( IF 2.5 ) Pub Date : 2019-12-13 , DOI: 10.1021/acs.organomet.9b00102
Daniel Lupp ₁ , Kuo-Wei Huang ₁

Affiliation

We studied the mechanism of the pyrrole synthesis catalyzed by a PN³P–Mn pincer ligand system and show that a bifunctional double hydrogen transfer mechanism is favored over the alternative β-hydride elimination. Both dehydrogenation and hydrogen-formation steps benefit from proton shuttles, with alcohol-mediated processes being consistently favored, leading to energy barriers that, in good agreement with the experimental results, are similar to those for the previously reported corresponding iridium-catalyzed process. We also show that the coordination of one potassium ion to the ligand lowers the energy barriers for the key steps. The overall rate-determining step is the regeneration of the catalyst with an energy barrier of 30.7 kcal/mol with potassium and 31.1 kcal/mol without potassium. Our results support the involvement and the importance of the aromatization/dearomatization paradigm in the reaction.

中文翻译：

磷氮PN ³ P平台中金属-配体协同作用的重要性：Mn催化吡咯合成的计算研究

我们研究了PN ³催化吡咯合成的机理P-Mn钳夹配体系统，并表明双功能双氢转移机制优于替代性的β-氢化物消除。脱氢步骤和氢形成步骤都受益于质子穿梭，一直以来都支持醇介导的过程，从而导致能垒与实验结果非常相似，与先前报道的相应的铱催化过程相似。我们还表明，一个钾离子与配体的配位降低了关键步骤的能垒。总体决定速率的步骤是催化剂的再生，其能量垒为含钾30.7 kcal / mol和不含钾31.1 kcal / mol。我们的结果支持了芳构化/脱芳构化范式在反应中的参与和重要性。

更新日期：2019-12-13

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