Electrocatalytic Hydrogen Evolution by Cobalt Complexes with a Redox Non-Innocent Polypyridine Ligand
Autor: | Ya-Qiong Zhang, Frank W. Heinemann, Lianpeng Tong, Jiale Liu, Karsten Meyer, Rong-Zhen Liao, Randolph P. Thummel |
---|---|
Rok vydání: | 2021 |
Předmět: | |
Zdroj: | Inorganic Chemistry. 60:17976-17985 |
ISSN: | 1520-510X 0020-1669 |
DOI: | 10.1021/acs.inorgchem.1c02539 |
Popis: | Novel cobalt and zinc complexes with the tetradentate ppq (8-(1″,10″-phenanthrol-2″-yl)-2-(pyrid-2'-yl)quinoline) ligand have been synthesized and fully characterized. Electrochemical measurements have shown that the formal monovalent complex [Co(ppq)(PPh3)]+ (2) undergoes two stepwise ligand-based electroreductions in DMF, affording a [Co(ppq)DMF]-1 species. Theoretical calculations have described the electronic structure of [Co(ppq)DMF]-1 as a low-spin Co(II) center coupling with a triple-reduced ppq radical ligand. In the presence of triethylammonium as the proton donor, the cobalt complex efficiently drives electrocatalytic hydrogen evolution with a maximum turnover frequency of thousands per second. A mechanistic investigation proposes an EECC H2-evolving pathway, where the second ligand-based redox process (E), generating the [Co(ppq)DMF]-1 intermediate, initiates proton reduction, and the second proton transfer process (C) is the rate-determining step. This work provides a unique example for understanding the role of redox-active ligands in electrocatalytic H2 evolution by transition metal sites. |
Databáze: | OpenAIRE |
Externí odkaz: |
Pro tento záznam nejsou dostupné žádné jednotky.