Department of Chemistry, University of Virginia, McCormick Rd, PO Box 400319, Charlottesville, Virginia 22904-4319, USA.
Chem Commun (Camb). 2021 Jan 14;57(4):516-519. doi: 10.1039/d0cc06763f. Epub 2020 Dec 17.
We report a Co-based complex for the reduction of O to HO utilizing decamethylferrocene as chemical reductant and acetic acid as a proton donor in methanol solution. Despite structural similarities to previously reported Co(NO) complexes capable of catalytic O reduction, this system shows selectivity for the four-electron/four-proton reduction product, HO, instead of the two-electron/two-proton reduction product, HO. Mechanistic studies show that the overall rate law is analogous to previous examples, suggesting that the key selectivity difference arises in part from increased favorability of protonation at the distal O position of the key intermediate Co(iii)-hydroperoxide, instead of the proximal one. Interestingly, no product selectivity dependence is observed with respect to the presence of pyridine, which is proposed to bind trans to O during catalysis.
我们报告了一种基于钴的配合物，用于在甲醇溶液中利用十甲基二茂铁作为化学还原剂和乙酸作为质子供体将 O 还原为 HO。尽管与之前报道的能够催化 O 还原的 Co(NO)配合物具有结构相似性，但该体系对四电子/四质子还原产物 HO 表现出选择性，而不是对二电子/二质子还原产物 HO 表现出选择性。机理研究表明，总速率定律与以前的例子类似，这表明关键选择性差异部分源于关键中间体 Co(iii)-过氧化物中远端 O 位置的质子化变得更加有利，而不是近端 O 位置。有趣的是，在催化过程中吡啶的存在与否对产物选择性没有影响，吡啶被提议在催化过程中与 O 反式结合。
