Hastreiter Florian, Lorenz Corinna, Hioe Johnny, Gärtner Stefanie, Lokesh Nanjundappa, Korber Nikolaus, Gschwind Ruth M
Organic Chemistry, University of Regensburg, 93040, Regensburg, Germany.
Inorganic Chemistry, University of Regensburg, 93040, Regensburg, Germany.
Angew Chem Int Ed Engl. 2019 Mar 4;58(10):3133-3137. doi: 10.1002/anie.201812955. Epub 2019 Jan 29.
The existence of [μ-HSi ] in liquid ammonia solutions is confirmed by H and Si NMR experiments. Both NMR and quantum chemical calculations reveal that the H atom bridges two Si atoms of the [Si ] cluster, contrary to the expectation that it is located at one vertex Si of the tetrahedron. The calculations also indicate that in the formation of [μ-HSi ] , protonation is driven by a high charge density and an increase of electron delocalization compared to [Si ] . Additionally, [Si ] was detected for the first time and characterized by NMR. Calculations show that it is resistant to protonation, owing to a strong charge delocalization, which is significantly reduced upon protonation. Thus, our methods reveal three silicides in liquid ammonia: unprotonated [Si ] , terminally protonated [HSi ] , and bridge-protonated [μ-HSi ] . The protonation trend can be roughly predicted by the difference in charge delocalization between the parent compound and the product, which can be finely tuned by the presence of counter ions in solution.
通过氢和硅的核磁共振实验证实了液氨溶液中[μ-HSi ]的存在。核磁共振和量子化学计算均表明，氢原子桥连[Si ]簇的两个硅原子，这与预期其位于四面体的一个顶点硅原子处相反。计算还表明，在[μ-HSi ]的形成过程中，与[Si ]相比，质子化是由高电荷密度和电子离域增加驱动的。此外，首次检测到[Si ]并通过核磁共振对其进行了表征。计算表明，由于电荷强烈离域，它对质子化具有抗性，质子化后电荷离域会显著降低。因此，我们的方法揭示了液氨中的三种硅化物：未质子化的[Si ]、末端质子化的[HSi ]和桥连质子化的[μ-HSi ]。质子化趋势可以通过母体化合物和产物之间电荷离域的差异大致预测，溶液中抗衡离子的存在可以对其进行精细调节。
