Institut für Chemie, Technische Universität Berlin, 10623 Berlin, Germany.
Science. 2019 Jul 12;365(6449):168-172. doi: 10.1126/science.aax9184.
Hydrogen-substituted silylium ions are long-sought reactive species. We report a protolysis strategy that chemoselectively cleaves either an Si-C(sp) or an Si-H bond using a carborane acid to access the full series of [CHBHBr]-stabilized RSiH, RSiH , and SiH cations, where bulky -butyl groups at the silicon atom (R = Bu) were crucial to avoid substituent redistribution. The crystallographically characterized molecular structures of [CHBHBr]-stabilized BuHSi and BuHSi feature pyramidalization at the silicon atom, in accordance with that of BuSi[CHBHBr] Conversely, the silicon atom in the HSi cation adopts a trigonal-planar structure and is stabilized by two counteranions. This solid-state structure resembles that of the corresponding Brønsted acid.
氢化硅鎓离子是人们长期以来一直追求的反应性物种。我们报告了一种质子化策略，该策略使用硼烷酸选择性地断裂 Si-C(sp) 或 Si-H 键，从而获得全系列的 [CHBHBr]-稳定的 RSiH、RSiH 和 SiH 阳离子，其中在硅原子上带有大体积的叔丁基基团（R = Bu）是至关重要的，以避免取代基重排。用硼烷酸稳定的 BuHSi 和 BuHSi 的晶体结构特征表明硅原子的三角锥形化，这与 BuSi[CHBHBr] 一致。相反，HSi 阳离子中的硅原子采用平面三角形结构，并由两个抗衡阴离子稳定。这种固态结构类似于相应的布朗斯台德酸。
