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Series of Fluorinated Benzimidazole-Substituted Nitronyl Nitroxides: Synthesis, Structure, Acidity, Redox Properties, and Magnetostructural Correlationsстатья
Статья опубликована в высокорейтинговом журнале
Статья опубликована в журнале из списка Web of Science и/или Scopus- Авторы: Tretyakov Evgeny, Fedyushin Pavel, Bakuleva Nadejda, Korlyukov Alexander, Dorovatovskii Pavel, Gritsan Nina, Dmitriev Alexey, Akyeva Anna, Syroeshkin Mikhail, Stass Dmitri, Zykin Mikhail, Efimov Nikolay, Luneau Dominique
- Журнал: Journal of Organic Chemistry
- Том: 88
- Номер: 15
- Год издания: 2022
- Издательство: American Chemical Society
- Местоположение издательства: United States
- Первая страница: 10355
- Последняя страница: 10370
- DOI: 10.1021/acs.joc.2c01793
- Аннотация: A special series of nitronyl nitroxides was synthesized: 2-(benzimidazol-2′-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyls mono-, di-, tri-, or tetrafluorinated on the benzene ring. The structure of all paramagnets was unambiguously confirmed by single-crystal X-ray diffraction. It was found that in crystals, the radicals are assembled into chains due to intermolecular H-bonds between the benzimidazole moiety (H-bond donor) and the nitronyl nitroxide group or benzimidazole ring (H-bond acceptor). The magnetic properties of nitronyl nitroxides depend on the type of binding of radicals by H-bonds. The magnetic motif of 4-fluoro-, 5-fluoro-, 4,6-difluoro-, 4,5,6-trifluoro-, 4,5,7-trifluoro-, and 4,5,6,7-tetrafluoro-derivatives, as well as the nonfluorinated compound, consists of ferromagnetic chains (J/kB ≈ 20–40 K) formed by the McConnell type I mechanism. In the 5,6-difluoro- and 4,5-difluoro-derivatives, the distances between the paramagnetic centers are large, as a result of which the exchange interactions are weak. According to cyclic voltammetry, paramagnets are oxidized reversibly, while their reduction is a quasi-reversible electron transfer (EC mechanism); experimental redox potentials of radicals correlate well with the calculated values. Quantum chemical assessment of the acidity of benzimidazolyl-substituted nitronyl nitroxides revealed that the introduction of fluorine atoms into the benzene ring enhances the acidity of the paramagnets by more than 5 orders of magnitude.
- Добавил в систему: Вологжанина Анна Владимировна