Zhang Jing, Liu Shihan, Zhang Tao, Liu Tao, Lan Yu
Department of Chemistry and Chemical Engineering, Jining University, Qufu 273155, P. R. China.
School of Chemistry and Chemical Engineering, and Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 400030, P. R. China.
Dalton Trans. 2021 Jun 8;50(22):7656-7666. doi: 10.1039/d1dt00399b.
Density functional theory (DFT) calculation has been used to reveal the mechanism of the Pd-catalyzed disilylation reaction of aryl halides. The DFT calculations indicate that the reaction starts with the oxidative addition of the C-I bond to the Pd(0) catalyst. Concerted metalation-deprotonation (CMD) can then generate a five-membered palladacycle. Insertion of Pd(ii) into the Si-Si bond in disilane followed by two sequential steps of reductive eliminations yields the disilylation product and regenerates the Pd(0) catalyst. According to the NPA charge analysis along the reaction coordinates, the formal oxidative addition of the Si-Si bond to palladium could be considered as the insertion of palladium into the Si-Si bond. However, the conventional oxidative addition of the C-I bond to palladium is exactly an oxidation process with the electron transfer from the palladium atom to the C-I bond. Therefore, electron rich Pd(0) is beneficial for the oxidation process, and Pd(ii) prone to acquire electrons is beneficial for the insertion process.
密度泛函理论（DFT）计算已被用于揭示钯催化芳基卤化物的二硅化反应机理。DFT计算表明，反应始于芳基碘（C-I）键向钯（0）催化剂的氧化加成。协同金属化-去质子化（CMD）随后可生成一个五元钯环。钯（II）插入乙硅烷中的硅-硅键，随后经过两步连续的还原消除反应，生成二硅化产物并使钯（0）催化剂再生。根据沿反应坐标的自然键轨道（NPA）电荷分析，硅-硅键向钯的形式氧化加成可视为钯插入硅-硅键。然而，传统的芳基碘（C-I）键向钯的氧化加成实际上是一个氧化过程，电子从钯原子转移至芳基碘（C-I）键。因此，富电子的钯（0）有利于氧化过程，而易于获取电子的钯（II）有利于插入过程。
