Max-Planck-Institut für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany.
Inorg Chem. 2020 Oct 5;59(19):14251-14262. doi: 10.1021/acs.inorgchem.0c02041. Epub 2020 Sep 20.
Nature utilizes multimetallic sites in metalloenzymes to enable multielectron chemical transformations at ambient conditions and low overpotentials. One such example of multimetallic cooperativity can be found in the C-cluster of Ni-carbon monoxide dehydrogenase (CODH), which interconverts CO and CO. Toward a potential functional model of the C-cluster, a family of Ni-Fe bimetallic complexes was synthesized that contain direct metal-metal bonding interactions. The complexes were characterized by X-ray crystallography, various spectroscopies (NMR, EPR, UV-vis, Mössbauer), and theoretical calculations. The Ni-Fe bimetallic system has a reversible Fe(III)/Fe(II) redox couple at -2.10 V (vs Fc/Fc). The Fe-based "redox switch" can turn on CO reactivity at the Ni(0) center by leveraging the Ni→Fe dative interaction to attenuate the Ni(0) electron density. The reduced Ni(0)Fe(II) species mediated the formal two-electron reduction of CO to CO, providing a Ni-CO adduct and CO as products. During the reaction, an intermediate was observed that is proposed to be a Ni-CO species.
自然界利用金属酶中的多金属位点,在环境条件和低过电势下实现多电子化学反应转化。在镍-一氧化碳脱氢酶 (CODH) 的 C 簇中可以找到多金属协同作用的一个例子,该 C 簇可以相互转化 CO 和 CO。为了得到 C 簇的潜在功能模型,合成了一系列含有直接金属-金属键合相互作用的镍-铁双金属配合物。通过 X 射线晶体学、各种光谱学(NMR、EPR、UV-vis、Mössbauer)和理论计算对配合物进行了表征。该镍-铁双金属体系在 -2.10 V(相对于 Fc/Fc)处具有可逆的 Fe(III)/Fe(II)氧化还原对。基于铁的“氧化还原开关”可以通过利用 Ni→Fe 配位相互作用来削弱 Ni(0)的电子密度,从而使 CO 在 Ni(0)中心具有反应活性。还原的 Ni(0)Fe(II)物种介导了 CO 的形式两电子还原为 CO,生成 Ni-CO 加合物和 CO 作为产物。在反应过程中,观察到一个中间体,该中间体被认为是 Ni-CO 物种。