Water provides an ideal source for the production of protons and electrons required for generation of renewable fuels. Among the most-prominent electrocatalysts capable of water oxidation at low overpotentials are Ru(bda)L₂-type catalysts. Although many studies were dedicated to the investigation of the influence of structural variations, the true implication of the bda backbone on catalysis remains mostly unclarified. In this work, we further investigated if electronic effects are contributing to catalysis by Ru(bda)(pic)₂ or if the intrinsic catalytic activity mainly originates from the structural features of the ligand. Through introduction of pyrazines in the bda backbone, forming Ru(N¹-bda)(pic)₂ and Ru(N²-bda)(pic)₂, electronic differences were maximized while minimizing changes in the geometry and other intermolecular interactions. Through a combination of electrochemical analysis, chemical oxygen evolution, and density functional theory calculations, we reveal that the catalytic activity is unaffected by the electronic features of the backbone and that the unique bimolecular reactivity of the Ru(bda)L₂ family of catalysts thus purely depends on the spatial geometry of the ligand.

中文翻译：

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2,2'-联吡啶-6,6'-二羧酸盐配体在Ru基分子水氧化催化剂中的电子影响

水是产生可再生燃料所需的质子和电子生产的理想来源。Ru（bda）L ₂型催化剂是能够在低超电势下进行水氧化的最杰出的电催化剂。尽管许多研究致力于研究结构变异的影响，但bda骨架对催化的真实含义仍未明确。在这项工作中，我们进一步研究了电子效应是否有助于Ru（bda）（pic）₂的催化作用，或者固有催化活性是否主要源自配体的结构特征。通过在bda骨架中引入吡嗪，形成Ru（N ¹ -bda）（pic）₂和Ru（N ² -bda）（pic）₂，电子差异最大化，同时最小化几何形状和其他分子间相互作用的变化。通过电化学分析，化学氧逸出和密度泛函理论计算的组合，我们揭示了催化活性不受骨架电子特性的影响，因此Ru（bda）L ₂族独特的双分子反应活性纯粹取决于配体的空间几何形状。