Twofold oxidized and twofold protonated redox-active guanidine: An ultimate intermediate in proton-coupled electron-transfer reactions
Due to their high Brønsted basicity and redox properties, guanidino-functionalized aromatics (GFAs) are privileged proton-coupled electron-transfer (PCET) reagents. Herein we show that the GFA 1,2,4,5-tetrakis(tetramethylguanidino)-benzene (1), after being oxidized to the green dicationic state (12+...
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| Main Authors: | , , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
19 September 2018
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| In: |
European journal of organic chemistry
Year: 2018, Issue: 43, Pages: 5910-5915 |
| ISSN: | 1099-0690 |
| DOI: | 10.1002/ejoc.201801378 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1002/ejoc.201801378 Verlag, lizenzpflichtig, Volltext: https://onlinelibrary.wiley.com/doi/abs/10.1002/ejoc.201801378 
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| Author Notes: | Ute Wild, Olaf Hübner, Lutz Greb, Markus Enders, Elisabeth Kaifer, and Hans-Jörg Himmel |
| Summary: | Due to their high Brønsted basicity and redox properties, guanidino-functionalized aromatics (GFAs) are privileged proton-coupled electron-transfer (PCET) reagents. Herein we show that the GFA 1,2,4,5-tetrakis(tetramethylguanidino)-benzene (1), after being oxidized to the green dicationic state (12+), can bind one or two protons, resulting in the blue monoprotonated trication (1+H)3+ and the orange diprotonated tetracation (1+2H)4+, realizing the first purely organic PCET reagent that can be diprotonated in its oxidized state. With trifluoroacetate counterions, low-barrier hydrogen-bonding is observed, allowing to shift protons reversibly in dependence of the temperature and solvent polarity between 12+ and trifluoroacetate. The protonation of 12+ has dramatic effects on its oxidation capabilities. |
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| Item Description: | Gesehen am 19.03.2020 |
| Physical Description: | Online Resource |
| ISSN: | 1099-0690 |
| DOI: | 10.1002/ejoc.201801378 |