EaStCHEM School of Chemistry, University of St. Andrews , St. Andrews, Fife KY16 9ST, United Kingdom.
Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States.
J Am Chem Soc. 2017 Nov 22;139(46):16514-16517. doi: 10.1021/jacs.7b10788. Epub 2017 Nov 9.
Three-member ring boracyclopropanes (boriranes) with N-heterocyclic carbene substituents were prepared by a recently discovered route. H atoms were selectively abstracted from the boron atoms by t-butoxyl radicals and this enabled boriranyl radicals to be detected and characterized by EPR spectroscopy for the first time. Their EPR parameters indicated they had planar π-character. From competition experiments, the rate constant for H atom abstraction was determined and found to be about 2 orders of magnitude less than for NHC-boranes. The B-H BDE of an NHC-borirane was estimated to be about 95 kcal mol.
具有 N-杂环卡宾取代基的三员环硼环丙烷（硼烷）是通过最近发现的路线制备的。通过叔丁氧基自由基选择性地从硼原子上提取 H 原子，这使得硼烷自由基首次被检测和通过 EPR 光谱进行表征。它们的 EPR 参数表明它们具有平面的π-特征。通过竞争实验，确定了 H 原子提取的速率常数，发现其比 NHC-硼烷小约 2 个数量级。NHC-硼烷的 B-H BDE 估计约为 95 kcal mol。
