我们在本文中描述了具有多功能联吡啶二膦酸酯配体的钌配合物的合成和表征,以及初始水氧化研究。在这些络合物中,膦酸酯基团通过电荷补偿和σ贡献提供了氧化还原电位的平衡,从而可以轻松地进入高氧化态。这些配合物表现出独特的pH依赖性电化学,与膦酸基团的去质子化有关。这些基团的位置使它们能够将质子穿入和穿出催化部位,并减少活化障碍。在实验结果和DFT计算的基础上,提出了利用这些催化剂进行水氧化的机理。中性六坐标上前所未有的水攻击[Ru IV中心产生阴离子的七坐标[Ru IV -OH] -中间体是其中所有物种均为阴离子或中性的单部位机理的关键步骤之一。这些络合物是迄今为止报道的最快的单中心催化剂。
Bridging of Bipyridine Units by Phenylphosphine Links: Linear and Cyclic Oligomers and Some Acid Derivatives
摘要:
Reaction of 6,6'-dibromo-2,2'-bipyridine with phenylphosphine under palladium-promoted cross-coupling conditions provides a variety of linear oligomers bearing two reactive bromo substituents as well as a cyclic dimer, characterized by X-ray crystallography, in which the bipyridine units are constrained to a cis configuration by two phenylphosphine oxide bridges. Derivatives of the linear species containing both carboxylate and phosphonate substituents are readily obtained.