Department of Chemical and Biological Engineering, University of Wisconsin-Madison , 1415 Engineering Drive, Madison, Wisconsin 53706-1607, United States.
J Am Chem Soc. 2017 Jul 12;139(27):9156-9159. doi: 10.1021/jacs.7b05335. Epub 2017 Jun 27.
Hydrogenation of alkenes with C═C bonds is a ubiquitous reaction in organic chemistry. However, this transformation remains unknown for heavier counterparts, disilenes with Si═Si bonds. Here we report the isolation of (Z)-diiminodisilyldisilene 2 featuring a highly trans-bent and twisted structure and the longest silicon-silicon double bond reported to date. In silico studies suggested that the Si═Si bond in 2 is described as very weak double donor-acceptor bond. We utilized the remarkable electronic and structural features of this product to achieve the first demonstration of hydrogen activation by a multiply bonded silicon compound under ambient conditions. Interestingly, NMR and X-ray analysis gave exclusively racemic (RR/SS)-1,2-disilane 3a, indicating a stereospecific trans-hydrogenation of the Si═Si bond. In-depth calculations revealed that in strong contrast to the reactivity of C═C bonds, a concerted anti-addition pathway was favored due to the twisted structure of 2.
烯烃与 C═C 键的氢化反应是有机化学中普遍存在的反应。然而，对于较重的同类物，即具有 Si═Si 键的二硅烯，这种转化仍然未知。在这里，我们报告了（Z）-二亚氨基二硅基二硅烯 2 的分离，其具有高度反式弯曲和扭曲的结构，以及迄今为止报道的最长的硅-硅双键。计算机研究表明，2 中的 Si═Si 键被描述为非常弱的双供体-受体键。我们利用该产物显著的电子和结构特性，首次在环境条件下实现了多重键合硅化合物对氢的活化。有趣的是，NMR 和 X 射线分析仅给出了外消旋（RR/SS）-1,2-二硅烷 3a，表明 Si═Si 键的立体特异性反式氢化。深入的计算表明，与 C═C 键的反应性形成鲜明对比的是，由于 2 的扭曲结构，有利于协同反加成途径。
