[Co(NHC)(CO)3]: Isolation and Reactivity Study of a Model 17-Electron Species in the Oxo Process
[Co(NHC)(CO)3]: Isolation and Reactivity Study of a Model 17-Electron Species in the Oxo Process
复制标题
[Co(NHC)(CO)3]：羰基合成过程中模型 17 电子物种的分离和反应性研究
DOI：
10.1021/acs.organomet.0c00765
复制
发表时间：
2021
期刊：
影响因子：
2.8
通讯作者：
Fayzullin Robert R.
中科院分区：
文献类型：
--
作者：
Takebayashi Satoshi;Fayzullin Robert R.
[Co(L)(CO)3]2(L=CO或Pr3)催化的烯烃氢甲酰化反应是最成功的均相金属有机催化剂之一。双金属配合物[Co(L)(CO)3]2与其单核17电子配合物[Co(L)(CO)3]处于平衡状态。然而，单核金属化合物的分离还不清楚，因此这种物种在催化循环中的作用很难研究。在这里，我们报道了用扩环N-杂环卡宾(ReNHC)配体分离[Co(L)(CO)3]。这种络合物的分离使我们能够研究[Co(L)(CO)3]金属化合物对H_2进行三分子活化的可能性。动力学实验表明，[Co(ReNHC)(CO)3]不是通过先前提出的三分子机理激活H_2，而是通过双分子机理活化H_2。所得结果将有助于设计一种在温和条件下活化H_2的钴羰基络合物，并开发一种基于经济型钴催化剂的更节能的氧代工艺。
[Co(L)(CO)3]2(L = CO or PR3) catalyzed hydroformylation of olefins is among the most successful homogeneous organometallic catalysis. The bimetallic [Co(L)(CO)3]2complex exists in equilibrium with its mononuclear 17-electron [Co(L)(CO)3] metalloradical. However, isolation of the mononuclear metalloradical is unknown, and hence the role of this species in the catalytic cycle is difficult to study. Herein, we report the isolation of [Co(L)(CO)3] using ring-expanded N-heterocyclic carbene (reNHC) ligands. Isolation of this complex enabled us to examine feasibility of putative termolecular H2activation by the [Co(L)(CO)3] metalloradicals. The kinetic experiments revealed that [Co(reNHC)(CO)3] does not activate H2via a previously proposed termolecular mechanism but via a bimolecular mechanism. The result obtained here will contribute to design a cobalt carbonyl complex that activates H2under mild conditions and to develop a more energy efficient oxo process based on economical cobalt catalysts.