Brückner Tobias, Fantuzzi Felipe, Stennett Tom E, Krummenacher Ivo, Dewhurst Rian D, Engels Bernd, Braunschweig Holger
Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97070, Würzburg, Germany.
Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97070, Würzburg, Germany.
Angew Chem Int Ed Engl. 2021 Jun 7;60(24):13661-13665. doi: 10.1002/anie.202102218. Epub 2021 May 1.
The NHC-stabilised diboryne (B (SIDep) ; SIDep=1,3-bis(2,6-diethylphenyl)imidazolin-2-ylidene) undergoes a high-yielding P-P bond activation with tetraethyldiphosphine at room temperature to form a B P heterocycle via a diphosphoryldiborene by 1,2-diphosphination. The heterocycle can be oxidised to a radical cation and a dication, respectively, depending on the oxidant used and its counterion. Starting from the planar, neutral 1,3-bis(alkylidene)-1,3-diborata-2,4-diphosphoniocyclobutane, each oxidation step leads to decreased B-B distances and loss of planarity by cationisation. X-ray analyses in conjunction with DFT and CASSCF/NEVPT2 calculations reveal closed-shell singlet, butterfly-shaped structures for the NHC-stabilised dicationic B P rings, with their diradicaloid, planar-ring isomers lying close in energy.
由国家卫生健康委员会稳定的双硼炔（B(SIDep)；SIDep = 1,3 - 双(2,6 - 二乙基苯基)咪唑啉 - 2 - 亚基）在室温下与四乙基二膦发生高产率的P - P键活化反应，通过二膦酰化双硼烯经1,2 - 二膦化作用形成一个B - P杂环。根据所使用的氧化剂及其抗衡离子，该杂环可分别被氧化为自由基阳离子和二价阳离子。从平面、中性的1,3 - 双(亚烷基)-1,3 - 二硼杂-2,4 - 二膦环丁烷出发，每一步氧化都会导致B - B距离缩短以及阳离子化作用使平面性丧失。结合密度泛函理论（DFT）和完全活性空间自洽场/内收缩多参考二级微扰理论（CASSCF/NEVPT2）计算的X射线分析揭示了由国家卫生健康委员会稳定的二价阳离子B - P环具有闭壳层单重态、蝴蝶形结构，其双自由基oid平面环异构体的能量与之相近。
