Catalytic dioxygen reduction mediated by a tetranuclear cobalt complex supported on a stannoxane core
| Autor: | Uwe Kuhlmann, Peter Hildebrandt, Anirban Chandra, Kallol Ray, Holger Dau, Subrata Kundu, Stefan Mebs |
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| Rok vydání: | 2020 |
| Předmět: |
Ligand
500 Naturwissenschaften und Mathematik::530 Physik::530 Physik chemistry.chemical_element Photochemistry Stannoxane law.invention Catalysis Inorganic Chemistry Chemical kinetics chemistry.chemical_compound low-temperature spectroscopic (UV-Vis resonance Raman andX-ray absorption spectroscopies Catalytic dioxygen reduction chemistry law Yield (chemistry) ddc:540 catalysts in fuel cells Selectivity Electron paramagnetic resonance Cobalt |
| Zdroj: | Dalton Transactions. 49:6065-6073 |
| ISSN: | 1477-9234 1477-9226 |
| DOI: | 10.1039/d0dt00475h |
| Popis: | The synthesis, spectroscopic characterization (infrared, electron paramagnetic resonance and X-ray absorption spectroscopies) and density functional theoretical calculations of a tetranuclear cobalt complex Co4L1 involving a nonheme ligand system, L1, supported on a stannoxane core are reported. Co4L1, similar to the previously reported hexanuclear cobalt complex Co6L2, shows a unique ability to catalyze dioxygen (O2) reduction, where product selectivity can be changed from a preferential 4e−/4H+ dioxygen-reduction (to water) to a 2e−/2H+ process (to hydrogen peroxide) only by increasing the temperature from −50 to 30 °C. Detailed mechanistic insights were obtained on the basis of kinetic studies on the overall catalytic reaction as well as by low-temperature spectroscopic (UV-Vis, resonance Raman and X-ray absorption spectroscopies) trapping of the end-on μ-1,2-peroxodicobalt(III) intermediate 1. The Co4L1- and Co6L2-mediated O2-reduction reactions exhibit different reaction kinetics, and yield different ratios of the 2e−/2H+ and 4e−/4H+ products at −50 °C, which can be attributed to the different stabilities of the μ-1,2-peroxodicobalt(III) intermediates formed upon dioxygen activation in the two cases. The deep mechanistic insights into the transition-metal mediated dioxygen reduction process that are obtained from the present study should serve as useful and broadly applicable principles for future design of more efficient catalysts in fuel cells. |
| Databáze: | OpenAIRE |
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