Mechanisms and origins of switchable regioselectivity of palladium- and nickel-catalyzed allene hydrosilylation with N-heterocyclic carbene ligands: a theoretical study.
Mechanisms and origins of switchable regioselectivity of palladium- and nickel-catalyzed allene hydrosilylation with N-heterocyclic carbene ligands: a theoretical study.
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DOI：
10.1021/jo500557w
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发表时间：
2014-05
期刊：
影响因子：
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通讯作者：
Hujun Xie;Lijiang Zhao;Liu Yang;Qun-fang Lei;Wenjun Fang;C. Xiong
中科院分区：
文献类型：
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作者：
Hujun Xie;Lijiang Zhao;Liu Yang;Qun-fang Lei;Wenjun Fang;C. Xiong
采用密度泛函理论（DFT）方法研究了钯和镍催化的联烯硅氢加成反应的机理和起源。自由能分布的Pd-和Ni-催化反应与小和大体积的N-杂环卡宾（NHC）配体的计算，以确定区域选择性的机制。计算结果表明，不同的金属（Ni和Pd）导致的区域化学反转的联烯硅氢加成。在钯催化下，小分子NHC配体的主要产物是烯丙基硅烷，而在镍催化下，大分子NHC配体的主要产物是乙烯基硅烷。电子和空间位阻因素对Pd和Ni催化的联烯硅氢加成反应的区域选择性起着关键作用。计算结果与实测的区域选择性符合较好，为硅氢加成反应区域选择性催化剂的设计提供了依据。
The mechanisms and origins for the Pd- and Ni-catalyzed regioselective hydrosilylation of allene have been investigated by means of density functional theory (DFT) calculations. The free-energy profiles of Pd- and Ni-catalyzed reactions with small and bulky N-heterocyclic carbene (NHC) ligands are calculated to determine the mechanism for regioselectivities. The calculation results show that different metals (Ni vs Pd) lead to regiochemical reversals for the hydrosilylation of allene. The allylsilane is the major product via palladium catalysis with small NHC ligand, while the vinylsilane is the major product via nickel catalysis with bulky NHC ligand. Both electronic and steric factors play a key role in the regioselectivities for the hydrosilylation of allene via Pd and Ni catalysts. The calculation results are in good agreement with observed regioselectivities and could provide insights into the design of new catalysts for the regioselectivity of hydrosilylation reactions.