二配位硼阳离子 (R 2 B + ),称为硼离子,是一种化学物质,其中硼仅带有四个价电子,并且与假设的碳离子(R 2 C 2+ ) 等电子。尽管孤对供体取代基如氨基已经能够分离几种硼离子,但二芳基化和二烷基化硼衍生物仍然完全未被探索。在这里,我们介绍了 dimesitylborinium 离子的合成、结构和反应性,它表现出出乎意料的高热稳定性。X 射线晶体学和11由密度泛函理论计算支持的 B 核磁共振谱表明,硼离子在固态和溶液中均采用线性双配位结构。硼中心通过来自甲基基团的p π键稳定,并且不受反离子或溶剂分子的配位。这种二芳基硼离子具有特殊的路易斯酸度,接受来自 CO 2的一对电子以引起不寻常的脱氧反应。
Activation of H<sub>2</sub> and Et<sub>3</sub>SiH by the Borinium Cation [Mes<sub>2</sub>B]<sup>+</sup>: Avenues to Cations [MesB(μ-H)<sub>2</sub>(μ-Mes)BMes]<sup>+</sup> and [H<sub>2</sub>B(μ-H)(μ-Mes)B(μ-Mes)(μ-H)BH<sub>2</sub>]<sup>+</sup>
作者:Karlee L. Bamford、Zheng-Wang Qu、Douglas W. Stephan
DOI:10.1021/jacs.9b02510
日期:2019.4.17
Reaction of dihydrogen and the borinium cation salt [Mes(2)B][B(C6F5)(4)] gave an arene-stabilized mesityl-borenium cation, which isotopically scrambles HD. Similarly, reaction with triethylsilane gave the diboranium cation [MesB(mu-H)(2)(mu-Mes)BMes](+) featuring three bridge-bonds between two boron centers. Reaction of same (Mes(2)BH)(2) with Bronsted acid also afforded the same diboranium whereas the corresponding reaction with (MesBH(2))(2) yielded the triboron cation [H2B(mu-H)(mu-Mes)B(mu-Mes)(mu-H)BH2](+).