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https://doi.org/10.1002/anie.202210697
Title: | “[8]Cyclo-para-phenylmethine as A Super-Cyclooctatetraene: Dynamic Behavior, Global Aromaticity, and Open-Shell Diradical Character in The Neutral and Dicationic States | Authors: | Z. Li X. Hou Y. Han W. Fan Y. Ni Q. Zhou J. Zhu S. Wu K.-W. Huang J. Wu |
Issue Date: | 25-Aug-2022 | Publisher: | Wiley | Citation: | Z. Li, X. Hou, Y. Han, W. Fan, Y. Ni, Q. Zhou, J. Zhu, S. Wu, K.-W. Huang, J. Wu (2022-08-25). “[8]Cyclo-para-phenylmethine as A Super-Cyclooctatetraene: Dynamic Behavior, Global Aromaticity, and Open-Shell Diradical Character in The Neutral and Dicationic States. Angew. Chem. Int. Ed. 61 (43) : e202210697. ScholarBank@NUS Repository. https://doi.org/10.1002/anie.202210697 | Rights: | Attribution 4.0 International | Abstract: | An [8]cyclo-para-phenylmethine derivative ([8]CPPM-Mes) was synthesized. X-ray analysis revealed a tub-shaped geometry similar to the cyclooctatetraene, with alternating benzenoid/quinoid structure. Variable-temperature NMR measurements disclosed a slow valence tautomerization process with an interconversion energy barrier of about 11.7 kcal mol−1 at coalescence temperature (273 K), and two more lower-barrier dynamic processes involving flipping of the 1,4-phenyl rings on the backbone and rotation of the mesityl substituents. Its dication ([8]CPPM-Mes2+) adopts a bowl-like geometry with a smaller depth of the cavity, and a slow bowl inversion process was observed by dynamic NMR. The bond lengths of the benzenoid/quinoid rings are more averaged via electron delocalization and the molecule shows global aromaticity, which was further validated by NMR and theoretical analysis. [8]CPPM-Mes2+ exhibits open-shell diradical character with a small singlet-triplet energy gap (−1.8 kcal mol−1). | Source Title: | Angew. Chem. Int. Ed. | URI: | https://scholarbank.nus.edu.sg/handle/10635/239205 | ISSN: | 1433-7851 1521-3773 |
DOI: | 10.1002/anie.202210697 | Rights: | Attribution 4.0 International |
Appears in Collections: | Staff Publications Elements |
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