title: Doubly N-Fused [24]Pentaphyrin Silicon Complex and Its Fluorosilicate: Enhanced Möbius Aromaticity in the Fluorosilicate.
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 SiIVcomplex 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.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
authors.forename: Shin-Ichiro
authors.initials: SI
authors.lastname: Ishida
authors.affiliation: Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, 120-749, Korea.
authors.forename: Jun Oh
authors.initials: JO
authors.lastname: Kim
authors.affiliation: Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, 120-749, Korea. dongho@yonsei.ac.kr.
authors.forename: Dongho
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan. osuka@kuchem.kyoto-u.ac.jp.
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Osuka
keywords: Möbius aromaticity; expanded porphyrins; pentaphyrin; silicates; silicon