Le Linh N V, Joyce Justin P, Oyala Paul H, DeBeer Serena, Agapie Theodor
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany.
J Am Chem Soc. 2024 Feb 28;146(8):5045-5050. doi: 10.1021/jacs.3c12025. Epub 2024 Feb 15.
Nitrogenases, the enzymes that convert N to NH, also catalyze the reductive coupling of CO to yield hydrocarbons. CO-coordinated species of nitrogenase clusters have been isolated and used to infer mechanistic information. However, synthetic FeS clusters displaying CO ligands remain rare, which limits benchmarking. Starting from a synthetic cluster that models a cubane portion of the FeMo cofactor (FeMoco), including a bridging carbyne ligand, we report a heterometallic tungsten-iron-sulfur cluster with a single terminal CO coordination in two oxidation states with a high level of CO activation (ν = 1851 and 1751 cm). The local Fe coordination environment (2S, 1C, 1CO) is identical to that in the protein making this system a suitable benchmark. Computational studies find an unusual intermediate spin electronic configuration at the Fe sites promoted by the presence the carbyne ligand. This electronic feature is partly responsible for the high degree of CO activation in the reduced cluster.
固氮酶是将N转化为NH的酶，它也催化CO的还原偶联以生成碳氢化合物。已分离出固氮酶簇的CO配位物种，并用于推断机理信息。然而，显示CO配体的合成FeS簇仍然很少，这限制了基准测试。从一个模拟铁钼辅因子（FeMoco）立方烷部分的合成簇开始，包括一个桥连卡宾配体，我们报道了一种异金属钨-铁-硫簇，在两种氧化态下具有单个末端CO配位，具有高水平的CO活化（ν = 1851和1751 cm）。局部Fe配位环境（2S，1C，1CO）与蛋白质中的相同，使该系统成为合适的基准。计算研究发现，卡宾配体的存在促进了Fe位点上不寻常的中间自旋电子构型。这种电子特征部分 responsible for the high degree of CO activation in the reduced cluster. （此处原文似乎有误，推测可能是“部分导致了还原簇中高度的CO活化”）
