Zhao Qianyi, Dewhurst Rian D, Braunschweig Holger, Chen Xuenian
Henan Key Laboratory of Boron Chemistry and Advanced Energy Materials, School of Chemistry and Chemical Engineering, Henan Normal University, 46 E. Jianshe Rd., Xinxiang, Henan, 453007, China.
Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
Angew Chem Int Ed Engl. 2019 Mar 11;58(11):3268-3278. doi: 10.1002/anie.201809733. Epub 2019 Jan 16.
A number of recently discovered nucleophilic boron compounds, such as boryl anions and borylenes, are breaking the rules regarding boron and boron-containing compounds and their reputation as Lewis acids/electrophiles. In a similar fashion, the B-H bonding pair electrons in boranes also show nucleophilicity which is ascribed to the lower electronegativity of boron relative to that of hydrogen. However, this nucleophilicity of the B-H bond has received far less attention. Explorations of the nucleophilicity of the B-H bonding pair electrons have led to the formation of B-H-B bonded units and B-H⋅⋅⋅H-Y dihydrogen bonds, based on which new chemistry has been uncovered, including the elucidation of the mechanism of formation of aminodiborane (ADB), the diammoniate of diborane (DADB), and lithium or sodium salts of octahydrotriborates (B H ), as well as the development of more convenient and straightforward synthetic routes to these reagents. Moreover, the recognition of the nucleophilic properties of the B-H bonding pair electrons will also help to more deeply understand the different mechanisms operating in hydroboration reactions.
最近发现的一些亲核性硼化合物，如硼基阴离子和硼烯，正在打破有关硼及含硼化合物的规则以及它们作为路易斯酸/亲电试剂的声誉。类似地，硼烷中的B-H键合电子对也表现出亲核性，这归因于硼的电负性低于氢。然而，B-H键的这种亲核性受到的关注要少得多。对B-H键合电子对亲核性的探索导致了B-H-B键合单元和B-H⋅⋅⋅H-Y双氢键的形成，在此基础上发现了新的化学性质，包括阐明氨基二硼烷（ADB）、硼烷二氨合物（DADB）和八氢三硼酸盐（BH）的锂盐或钠盐的形成机制，以及开发更方便直接的合成这些试剂的路线。此外，认识到B-H键合电子对的亲核性质也将有助于更深入地理解硼氢化反应中起作用的不同机制。
