The first palladium-catalyzed reductive cross-couplings of aryl chromium(0) carbene complexes with aryl iodides have been realized. This coupling reaction shows excellent functional group tolerance and high efficiency. Mechanistically, aryl chromium(0) carbene complexes undergo transmetalation with arylpalladium species to generate palladium(II) carbene intermediates, which is followed by migratory insertion. The catalytic cycle is then completed by hydrogen transfer and reductive elimination. Consistent with the mechanistic hypothesis, density functional theory (DFT) calculations support the involvement of a palladium carbene intermediate, and carbene migratory insertion is a facile step with an energy barrier of 5.1 kcal/mol. The carbene transfer step and the hydrogen transfer step are confirmed as the rate-limiting steps in the catalytic cycle.

中文翻译：

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钯催化芳基铬（0）费希尔碳化合物与芳基碘化物的还原交叉偶联反应

已经实现了芳族铬（0）卡宾配合物与芳基碘化物的第一个钯催化的还原交叉偶联。该偶联反应显示出优异的官能团耐受性和高效率。从机理上讲，芳基铬（0）卡宾配合物与芳基钯物种进行金属转移生成钯（II）卡宾中间体，然后迁移插入。然后通过氢转移和还原消除完成催化循环。与机理假说一致，密度泛函理论（DFT）计算支持钯卡宾中间体的参与，卡宾迁移插入是一个容易的步骤，其能垒为5.1 kcal / mol。卡宾转移步骤和氢转移步骤被确认为催化循环中的限速步骤。