Isolation and Identification of Pseudo Seven-Coordinate Ru(III) Intermediate Completing the Catalytic Cycle of Ru-bda Type of Water Oxidation Catalysts
Isolation and Identification of Pseudo Seven-Coordinate Ru(III) Intermediate Completing the Catalytic Cycle of Ru-bda Type of Water Oxidation Catalysts
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DOI：
10.31635/ccschem.021.202101159
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发表时间：
2022-07-01
期刊：
影响因子：
11.2
通讯作者：
Sun, Licheng
中科院分区：
文献类型：
--
作者：
Liu, Tianqi;Li, Ge;Sun, Licheng
由于违反了18电子规则，分离Ru-III-BDA(17电子物种)与水配体(2电子给体)的配合物是具有挑战性的。尽管Ru-BDA家族已经致力于水的氧化机理的研究，但Ru-III-BDA水合物的结构和初步形成仍然存在争议。在这里，我们通过设计口袋状的Ru基络合物1来挑战这一经常被忽视的步骤。计算研究表明，与经典的Ru-BDA催化剂相比，1在Ru-V(O)状态下具有关键的疏水性，并且与经典的Ru-BDA催化剂相比，其末端O与溶剂水分子的接触几率相似。通过对Ru-II和Ru-III态单晶结构的表征，观察到一种准七配位的“即用”水配体，Ru-III…O距离为3.62A。这种水配体也被发现是形成的氢键网络的一部分，这为Ru-III-OH2络合物的形成提供了一个很好的指示。
Isolation of Ru-III-bda (17-electron specie) complex with an aqua ligand (2-electron donor) is challenging due to violation of the 18-electron rule. Although considerable efforts have been dedicated to mechanistic studies of water oxidation by the Ru-bda family, the structure and initial formation of the Ru-III-bda aqua complex are still controversial. Herein, we challenge this often overlooked step by designing a pocketshape Ru-based complex 1. The computational studies showed that 1 possesses the crucial hydrophobicity at the Ru-V(O) state as well as similar probability of access of terminal O to solvent water molecules when compared with classic Ru-bda catalysts. Through characterization of single-crystal structures at the Ru-II and Ru-III states, a pseudo seven-coordinate "ready-to-go" aqua ligand with Ru-III...O distance of 3.62 A was observed. This aqua ligand was also found to be part of a formed hydrogen-bonding network, providing a good indication of how the Ru-III-OH2 complex is formed.[GRAPHICS].