Doubly N‐Fused [24]Pentaphyrin Silicon Complex and Its Fluorosilicate: Enhanced Möbius Aromaticity in the Fluorosilicate |
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Authors: | Shin‐ichiro Ishida Jun Oh Kim Prof Dr Dongho Kim Prof Dr Atsuhiro Osuka |
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Institution: | 1. Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, Japan;2. Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, Korea |
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Abstract: | Treatment of nonaromatic N‐fused 24]pentaphyrin with trichloromethylsilane in the presence of a base afforded doubly N‐fused 24]pentaphyrin and its silicon complex. Addition of fluoride ion to the silicon complex led to the formation of its fluorosilicate as an unprecedented monoanionic six‐coordinated SiIV complex of porphyrinoid. Treatment of the fluorosilicate with acid led to the recovery of the silicon complex. The doubly N‐fused pentaphyrin, the silicon complex, and the fluorosilicate were all characterized as distinct Möbius aromatic molecules by spectroscopic measurements and X‐ray crystallographic analyses. Importantly, the second N‐fusion reaction, Si‐incorporation and fluoride addition to the Si‐atom enhanced the aromaticity of doubly N‐fused 24]pentaphyrins in this order. Tamao–Fleming oxidation of the silicon complex gave β‐keto doubly N‐fused pentaphyrin and triply fused 24]pentaphyrin, which were nonaromatic and Hückel anti‐aromatic, respectively. |
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Keywords: | expanded porphyrins Mö bius aromaticity pentaphyrin silicates silicon |
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