Mouchfiq Ahmed, Todorova Tanya K, Dey Subal, Fontecave Marc, Mougel Victor
Laboratoire de Chimie des Processus Biologiques , UMR 8229 CNRS , Collège de France , Sorbonne Universitè , 11 Place Marcelin Berthelot , 75231 Paris Cedex 05 , France . Email:
Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1 , CH-8093 Zürich , Switzerland . Email:
Chem Sci. 2020 May 18;11(21):5503-5510. doi: 10.1039/d0sc01045f. eCollection 2020 Jun 7.
Non-noble metal molecular catalysts mediating the electrocatalytic reduction of carbon dioxide are still scarce. This work reports the electrochemical reduction of CO to formate catalyzed by the bimetallic complex [(bdt)Mo(O)SCuCN] (bdt = benzenedithiolate), a mimic of the active site of the Mo-Cu carbon monoxide dehydrogenase enzyme (CODH2). Infrared spectroelectrochemical (IR-SEC) studies coupled with density functional theory (DFT) computations revealed that the complex is only a pre-catalyst, the active catalyst being generated upon reduction in the presence of CO. We found that the two-electron reduction of [(bdt)Mo(O)SCuCN] triggers the transfer of the oxo moiety to CO forming CO and the complex [(bdt)MoSCuCN] and that a further one-electron reduction is needed to generate the active catalyst. Its protonation yields a reactive MoH hydride intermediate which reacts with CO to produce formate. These findings are particularly relevant to the design of catalysts from metal oxo precursors.
介导二氧化碳电催化还原的非贵金属分子催化剂仍然稀缺。这项工作报道了由双金属配合物[(bdt)Mo(O)SCuCN]（bdt = 苯二硫醇盐）催化的CO电化学还原为甲酸盐的过程，该配合物是Mo-Cu一氧化碳脱氢酶（CODH2）活性位点的模拟物。红外光谱电化学（IR-SEC）研究与密度泛函理论（DFT）计算相结合表明，该配合物只是一种前催化剂，活性催化剂是在CO存在下还原时生成的。我们发现[(bdt)Mo(O)SCuCN]的双电子还原引发了氧代部分向CO的转移，形成CO 和配合物[(bdt)MoSCuCN]，并且需要进一步的单电子还原才能生成活性催化剂。其质子化产生一种反应性的MoH氢化物中间体，该中间体与CO反应生成甲酸盐。这些发现对于由金属氧代前体设计催化剂尤为重要。
