Suntrup Lisa, Stein Felix, Klein Johannes, Wilting Alexander, Parlane Fraser G L, Brown Christopher M, Fiedler Jan, Berlinguette Curtis P, Siewert Inke, Sarkar Biprajit
Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36, Berlin 14195, Germany.
Institut für Anorganische Chemie, Universität Göttingen, Tammannstraße 4, Göttingen 37077, Germany.
Inorg Chem. 2020 Apr 6;59(7):4215-4227. doi: 10.1021/acs.inorgchem.9b02591. Epub 2020 Mar 10.
Mesoionic carbenes have found wide use as components of homogeneous catalysts. Recent discoveries have, however, shown that metal complexes of such ligands also have huge potential in photochemical research and in the activation of small molecules. We present here three Re complexes with mesoionic pyridyl-carbene ligands. The complexes display reduction steps which were investigated via UV-vis-NIR-IR spectro-electrochemistry, and these results point toward an EC mechanism. The Re compounds emit in the visible range in solution at room temperature with excited state lifetimes that are dependent on the substituents of the mesoionic carbenes. These complexes are also potent electrocatalysts for the selective reduction of CO to CO. Whereas the substituents on the carbenes have no influence on the reduction potentials, the electrocatalytic efficiency is strongly dependent on the substituents. This fact is likely a result of catalyst instability. The results presented here thus introduce mesoionic carbenes as new potent ligands for the generation of emissive Re complexes and for electrocatalytic CO reduction.
中氮茚卡宾已被广泛用作均相催化剂的组分。然而，最近的发现表明，此类配体的金属配合物在光化学研究和小分子活化方面也具有巨大潜力。我们在此展示三种含有中氮茚吡啶 - 卡宾配体的铼配合物。这些配合物呈现出还原步骤，通过紫外 - 可见 - 近红外 - 红外光谱电化学对其进行了研究，这些结果指向一种EC机制。铼化合物在室温下于溶液中的可见光范围内发射，其激发态寿命取决于中氮茚卡宾的取代基。这些配合物也是将CO选择性还原为CO的有效电催化剂。虽然卡宾上的取代基对还原电位没有影响，但电催化效率强烈依赖于取代基。这一事实可能是催化剂不稳定性的结果。因此，本文展示的结果将中氮茚卡宾引入为用于生成发光铼配合物和用于电催化CO还原的新型有效配体。
