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Trishomoaromatic (B 3 N 3 Ph 6 ) Dianion: Characterization and Two‐Electron Reduction
Author(s) -
Li Nan,
Wu Botao,
Yu Chao,
Li Tianyu,
Zhang WenXiong,
Xi Zhenfeng
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201916651
Subject(s) - chemistry , borazine , rubidium , antiaromaticity , aromaticity , anthracene , boron , benzene , medicinal chemistry , electron , ether , selectivity , crystallography , inorganic chemistry , potassium , photochemistry , organic chemistry , boron nitride , molecule , catalysis , physics , quantum mechanics
Abstract Benzene, a common aromatic compound, can be converted into an unstable antiaromatic 8π‐electron intermediate through two‐electron reduction. However, as an isoelectronic equivalent of benzene, borazine (B 3 N 3 Ph 6 ), having weak aromaticity, undergoes a totally different two‐electron reduction to afford (B 3 N 3 R 6 ) 2− homoaromatic compounds. Reported here is the synthesis of homoaromatic (B 3 N 3 Ph 6 ) 2− by the reduction of B 3 N 3 Ph 6 with either potassium or rubidium in the presence of 18‐crown‐6 ether. Theoretical investigations illustrate that two electrons delocalize over the three boron atoms in (B 3 N 3 Ph 6 ) 2− , which is formed by the geometric and orbital reorganization and exhibits (π,σ)‐mixed homoaromaticity. Moreover, (B 3 N 3 Ph 6 ) 2− can act as a robust 2 e reductant for unsaturated compounds, such as anthracene, chalcone, and tanshinones. This 2 e reduction is of high efficiency and selectivity, proceeds under mild reaction conditions, and can regenerate neutral borazine.