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 pocket-shape 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 Å 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.

由于违反了 18 电子规则，用水配体（2 电子供体）分离 Ru ^III -bda（17 电子物质）复合物具有挑战性。尽管已经为 Ru-bda 家族对水氧化的机理研究做出了相当大的努力，但 Ru ^III -bda aqua 复合物的结构和初始形成仍然存在争议。在这里，我们通过设计一个袋状的 Ru 基复合物 1 来挑战这个经常被忽视的步骤。 计算研究表明 1 在 Ru ^V (O) 状态下具有关键的疏水性以及类似的终端 O 进入溶剂的可能性与经典的 Ru-bda 催化剂相比，水分子。通过表征 Ru ^II的单晶结构和 Ru ^III状态，观察到了一个伪七坐标“即用型”水配体，Ru ^III ⋯O 距离为 3.62 Å。还发现这种水配体是形成的氢键网络的一部分，很好地表明了 Ru ^III -OH ₂复合物是如何形成的。