Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania15213, United States.
Department of Chemistry, Southern Methodist University, Dallas, Texas75275, United States.
J Am Chem Soc. 2022 Sep 21;144(37):16905-16915. doi: 10.1021/jacs.2c05454. Epub 2022 Sep 9.
In this research article, we describe a 4H/4e electron-coupled-proton buffer (ECPB) based on Cu and a redox-active ligand. The protonated/reduced ECPB (complex : ), consisting of Cu with 2 equiv of the ligand (LH: 1,1'-(4,5-dimethoxy-1,2-phenylene)bis(3-(-butyl)urea)), reacted with H/e acceptors such as O to generate the deprotonated/oxidized ECPB. The resulting compound, (complex : ), was characterized by X-ray diffraction analysis, nuclear magnetic resonance (H-NMR), and density functional theory, and it is electronically described as a cuprous bis(benzoquinonediimine) species. The stoichiometric 4H/4e reduction of was carried out with H/e donors to generate (Cu and 2 equiv of LH) and the corresponding oxidation products. The ECPB system catalyzed the 4H/4e reduction of O to HO and the dehydrogenation of organic substrates in a decoupled (oxidations and reductions are separated in time and space) and a coupled fashion (oxidations and reductions coincide in time and space). Mechanistic analysis revealed that upon reductive protonation of and oxidative deprotonation of , fast disproportionation reactions regenerate complexes and in a stoichiometric fashion to maintain the ECPB equilibrium.
在这篇研究文章中，我们描述了一种基于 Cu 和氧化还原活性配体的 4H/4e 电子耦合质子缓冲剂 (ECPB)。质子化/还原的 ECPB（配合物：）由 Cu 与配体（LH：1,1'-(4,5-二甲氧基-1,2-亚苯基)双(3-(-丁基)脲)）的 2 当量组成，与 O 等 H/e 受体反应生成去质子化/氧化的 ECPB。所得化合物（配合物：）通过 X 射线衍射分析、核磁共振（H-NMR）和密度泛函理论进行了表征，并被电子描述为亚铜双（苯醌二亚胺）物种。用 H/e 供体进行的的化学计量学 4H/4e 还原生成（Cu 和 2 当量的 LH）和相应的氧化产物。ECPB 系统以解偶联（氧化和还原在时间和空间上分离）和偶联（氧化和还原在时间和空间上重合）的方式催化 O 的 4H/4e 还原为 HO 和有机底物的脱氢。机理分析表明，在和的还原质子化和的氧化去质子化后，快速歧化反应以化学计量方式再生配合物和以维持 ECPB 平衡。
