化学
催化作用
质子化
放射分析
水溶液
溶剂分解
催化循环
胺气处理
药物化学
反应速率常数
反应中间体
无机化学
物理化学
光化学
动力学
离子
有机化学
水解
物理
量子力学
作者
Brian N. DiMarco,Dmitry E. Polyansky,David C. Grills,Ping Wang,Yutaka Kuwahara,Xuan Zhao,Etsuko Fujita
出处
期刊:ChemPhysChem
[Wiley]
日期:2021-06-10
卷期号:22 (14): 1478-1487
被引量:3
标识
DOI:10.1002/cphc.202100295
摘要
Abstract In this work, the differences in catalytic performance for a series of Co hydrogen evolution catalysts with different pentadentate polypyridyl ligands (L), have been rationalized by examining elementary steps of the catalytic cycle using a combination of electrochemical and transient pulse radiolysis (PR) studies in aqueous solution. Solvolysis of the [Co II −Cl] + species results in the formation of [Co II (κ 4 ‐L)(OH 2 )] 2+ . Further reduction produces [Co I (κ 4 ‐L)(OH 2 )] + , which undergoes a rate‐limiting structural rearrangement to [Co I (κ 5 ‐L)] + before being protonated to form [Co III −H] 2+ . The rate of [Co III −H] 2+ formation is similar for all complexes in the series. Using E 1/2 values of various Co species and p K a values of [Co III −H] 2+ estimated from PR experiments, we found that while the protonation of [Co III −H] 2+ is unfavorable, [Co II −H] + reacts with protons to produce H 2 . The catalytic activity for H 2 evolution tracks the hydricity of the [Co II −H] + intermediate.
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