Radical Cation and Neutral Radical of Aza-thia[7]helicene with SOMO-HOMO Energy Level Inversion
| Autor: | Ying Wang, Andrzej Rajca, Suchada Rajca, Hui Zhang, Maren Pink, Arnon Olankitwanit |
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| Rok vydání: | 2016 |
| Předmět: |
010405 organic chemistry
General Chemistry 010402 general chemistry Ring (chemistry) Photochemistry 01 natural sciences Biochemistry Catalysis 0104 chemical sciences Ion chemistry.chemical_compound Colloid and Surface Chemistry chemistry Helicene Radical ion Molecular orbital Cyclic voltammetry HOMO/LUMO Pyrrole |
| Zdroj: | Journal of the American Chemical Society. 138(23) |
| ISSN: | 1520-5126 |
| Popis: | We report a relatively persistent, open-shell aza-thia[7]helicene with cross-conjugated electron-rich π-system. The singly occupied molecular orbital (SOMO) energy levels of both radical cation and neutral radical of the [7]helicene are below the highest occupied molecular orbital (HOMO) energy levels, thereby violating the Aufbau principle. The aza-thia[7]helicene is prepared from β-hexathiophene by a three-step one-pot reaction, in which the pyrrole ring is constructed by two consecutive C–N bond formations. Chemical oxidation converts the helicene to its radical cation, while in the presence of base (Cs2CO3), the oxidation gives neutral aminyl radical, likely via proton dissociation from the aminium radical cation with a low pKa. Reaction of the aza-thia[7]helicene with NaH provides the corresponding anion, which shows characteristic cyclic voltammetry wave at anodic peak potential Epa ≈ +0.2 V. Chemical oxidation of the anion with ferrocenium hexafluorophosphate at room temperature gives persistent ne... |
| Databáze: | OpenAIRE |
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