Structural and Electronic Influences on Rates of Tertpyridine−Amine Co III −H Formation During Catalytic H 2 Evolution in an Aqueous Environment
| Autor: | Brian N. DiMarco, Xuan Zhao, Dmitry E. Polyansky, David C. Grills, Ping Wang, Yutaka Kuwahara, Etsuko Fujita |
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| Rok vydání: | 2021 |
| Předmět: |
Aqueous solution
Chemistry Protonation 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Electrochemistry 01 natural sciences Medicinal chemistry Atomic and Molecular Physics and Optics 0104 chemical sciences Catalysis Catalytic cycle Radiolysis Amine gas treating Solvolysis Physical and Theoretical Chemistry 0210 nano-technology |
| Zdroj: | ChemPhysChem. 22:1478-1487 |
| ISSN: | 1439-7641 1439-4235 |
| DOI: | 10.1002/cphc.202100295 |
| Popis: | 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 [CoII -Cl]+ species results in the formation of [CoII (κ4 -L)(OH2 )]2+ . Further reduction produces [CoI (κ4 -L)(OH2 )]+ , which undergoes a rate-limiting structural rearrangement to [CoI (κ5 -L)]+ before being protonated to form [CoIII -H]2+ . The rate of [CoIII -H]2+ formation is similar for all complexes in the series. Using E1/2 values of various Co species and pKa values of [CoIII -H]2+ estimated from PR experiments, we found that while the protonation of [CoIII -H]2+ is unfavorable, [CoII -H]+ reacts with protons to produce H2 . The catalytic activity for H2 evolution tracks the hydricity of the [CoII -H]+ intermediate. |
| Databáze: | OpenAIRE |
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