An Anionic Aluminabenzene Bearing Aromatic and Ambiphilic Contributions

The synthesis and structure of an anionic aluminabenzene, which is the first example of an aluminum-containing heterobenzene, are reported. The molecular structure of this aluminabenzene exhibits a planar six-membered ring, and the absence of any bond alternation between its unsaturated bonds is consistent with the structural criteria of aromaticity. Theoretical calculations and the NMR spectroscopic analysis of this anionic aluminabenzene furthermore suggest that, in addition to the aromatic conjugation of six π-electrons, an ambiphilic contribution from a Lewis acidic aluminum center and an anionic pentadienyl moiety are present. Due to this contribution, the aluminabenzene is able to react with Lewis bases such as 4-dimethylaminopyridine and electrophiles such as methyl iodide.本研究报道了首例含铝杂苯类化合物——阴离子铝杂苯（anionic aluminabenzene）的合成与结构。该铝杂苯的分子结构呈现平面六元环，其不饱和键无键长交替现象，契合芳香性的结构判据。针对该阴离子铝杂苯的理论计算与核磁共振波谱分析进一步显示，除具备6π电子的芳香共轭体系外，其路易斯酸性铝中心与阴离子戊二烯基片段还存在两性贡献。得益于这一结构特性，该铝杂苯可与4-二甲氨基吡啶等路易斯碱、碘甲烷等亲电试剂发生反应。