Effect of N-heterocyclic carbene in palladium–tin heterobimetallic catalysis: a DFT supported study on the C3–H functionalization of unprotected indoles†

IF 5.4 3区材料科学 Q2 CHEMISTRY, PHYSICAL

ACS Applied Energy Materials Pub Date : 2024-08-12 DOI:10.1039/d4cy00224e

Mukesh Kumar Nayak , Rajat Rajiv Maharana , Anuradha Mohanty , Kousik Samanta , Sujit Roy

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Abstract

A new N-heterocyclic carbene (NHC)-based Pd–Sn heterobimetallic complex [(NHC)Pd(μ-Br)SnCl₃]₂ with low steric crowding in the active catalytic region was designed. The reactivity of this complex was compared with a previously reported NHC–Pd–Sn complex (NHC)₂PdBrSnCl₃ towards the C3–H functionalization of indoles with styrenes. The role of NHC in heterobimetallic catalysis was investigated in terms of the density functional theory by comparing the reactivity of these catalysts along with a cyclooctadiene (COD)-based Pd–Sn catalyst (COD)PdClSnCl₃. Thermochemical calculations revealed that the catalytic cycle is thermodynamically favorable in the case of the NHC-based catalysts but not in the case of the COD-based one. An inverse kinetic isotope effect with a k_H/k_D of 0.44 was detected. This alludes to the migration of a hydride from the metal center to the carbon center being the rate-determining step of the reaction. Based on the experimental and computational findings, an appropriate mechanism is proposed.

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钯锡杂二金属催化中 N-杂环碳烯的影响：对无保护吲哚的 C3-H 功能化的 DFT 支持研究

研究人员设计了一种新的基于 N-杂环碳烯 (NHC) 的钯锡杂双金属配合物 [(NHC)Pd(μ-Br)SnCl3]2，该配合物在活性催化区具有较低的立体拥挤。该复合物的反应活性与之前报道的 NHC-Pd-Sn 复合物 (NHC)2PdBrSnCl3 在吲哚与苯乙烯的 C3-H 功能化反应中的反应活性进行了比较。通过比较这些催化剂与基于环辛二烯（COD）的钯硒催化剂（COD）PdClSnCl3 的反应活性，用密度泛函理论研究了 NHC 在杂多金属催化中的作用。热化学计算显示，NHC 催化剂的催化循环在热力学上是有利的，而 COD 催化剂则不然。还检测到 kH/kD 为 0.44 的反向动力学同位素效应。这表明氢化物从金属中心迁移到碳中心是反应的决定性步骤。根据实验和计算结果，提出了一种适当的机理。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

ACS Applied Energy Materials Materials Science-Materials Chemistry

CiteScore

10.30

自引率

6.20%

发文量

1368

期刊介绍： ACS Applied Energy Materials is an interdisciplinary journal publishing original research covering all aspects of materials, engineering, chemistry, physics and biology relevant to energy conversion and storage. The journal is devoted to reports of new and original experimental and theoretical research of an applied nature that integrate knowledge in the areas of materials, engineering, physics, bioscience, and chemistry into important energy applications.