Martinez Jorge L, Schneider Joseph E, Anferov Sophie W, Anderson John S
Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States.
ACS Catal. 2023 Sep 14;13(19):12673-12680. doi: 10.1021/acscatal.3c02658. eCollection 2023 Oct 6.
Deoxygenation of nitrous oxide (NO) has significant environmental implications, as it is not only a potent greenhouse gas but is also the main substance responsible for the depletion of ozone in the stratosphere. This has spurred significant interest in molecular complexes that mediate NO deoxygenation. Natural NO reduction occurs via a Cu cofactor, but there is a notable dearth of synthetic molecular Cu catalysts for this process. In this work, we report a selective molecular Cu catalyst for the electrochemical reduction of NO to N using HO as the proton source. Cyclic voltammograms show that increasing the HO concentration facilitates the deoxygenation of NO, and control experiments with a Zn(II) analogue verify an essential role for Cu. Theory and spectroscopy support metal-ligand cooperative catalysis between Cu(I) and a reduced tetraimidazolyl-substituted radical pyridine ligand (MeImPPy = 2,6-(bis(bis-2--methylimidazolyl)phosphino)pyridine), which can be observed by Electron Paramagnetic Resonance (EPR) spectroscopy. Comparison with biological processes suggests a common theme of supporting electron transfer moieties in enabling Cu-mediated NO reduction.
一氧化二氮（N₂O）的脱氧具有重大的环境影响，因为它不仅是一种强效温室气体，还是平流层中臭氧消耗的主要物质。这激发了人们对介导N₂O脱氧的分子配合物的浓厚兴趣。天然的N₂O还原通过铜辅因子进行，但用于此过程的合成分子铜催化剂却明显匮乏。在这项工作中，我们报道了一种以HO⁻作为质子源，将N₂O电化学还原为N₂的选择性分子铜催化剂。循环伏安图表明，增加HO⁻浓度有助于N₂O的脱氧，用锌（II）类似物进行的对照实验证实了铜的关键作用。理论和光谱学支持了Cu（I）与还原的四咪唑基取代的自由基吡啶配体（MeImPPy = 2,6 -（双（双 - 2 - 甲基咪唑基）膦基）吡啶）之间的金属 - 配体协同催化作用，这可以通过电子顺磁共振（EPR）光谱观察到。与生物过程的比较表明，在实现铜介导的N₂O还原中，支持电子转移部分存在一个共同的主题。
