Probing the Most Aromatic and Antiaromatic Pyrrolium Rings by Maximizing Hyperconjugation and Push–Pull Effect |
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| Authors: | Tingting Sun Qiong Xie Dr Liang Zhao Dr Jun Zhu |
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| Institution: | 1. http://junzhu.chem8.org;2. State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, P. R. China;3. Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, P. R. China |
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| Abstract: | Hyperconjugation, a weak interaction in organic chemistry, can have a strong effect on aromaticity, leading to the concept of hyperconjugative aromaticity, which was first proposed by Mulliken in 1939. However, most studies are limited to main group chemistry. Here we report the most aromatic and antiaromatic pyrrolium ring by maximizing the hyperconjugation caused by transition metal fragments and the push–pull effect. Our calculations reveal that the origin of the outperformance of transition metal substituents over main group ones on hyperconjugative aromaticity could be attributed to their higher highest occupied molecular orbitals (HOMOs). Among the group 11 transition metals, a silver substituent results in the best performance. All these findings highlight the magic of the transition metal (silver) and could be particularly helpful for the design of other aromatic and antiaromatic counterparts based on a nonaromatic parent species. |
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| Keywords: | aromaticity hyperconjugation indolium push– pull effect pyrrolium |
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