Kyushin Soichiro, Kurosaki Yoshikuni, Otsuka Kyohei, Imai Haruna, Ishida Shintaro, Kyomen Toru, Hanaya Minoru, Matsumoto Hideyuki
Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, 376-8515, Japan.
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.
Nat Commun. 2020 Aug 11;11(1):4009. doi: 10.1038/s41467-020-17815-z.
A carbon-carbon double bond consists of a σ bond and a π bond. Recently, the concept of a π single bond, where a π bond is not accompanied by a σ bond, has been proposed in diradicals containing carbon and heteroatom radical centers. Here we report a closed-shell compound having a silicon-silicon π single bond. 1,2,2,3,4,4-Hexa-tert-butylbicyclo[1.1.0]tetrasilane has a silicon-silicon π single bond between the bridgehead silicon atoms. The X-ray crystallographic analysis shows that the silicon-silicon π single bond (2.853(1) Å) is far longer than the longest silicon-silicon bond so far reported. In spite of this unusually long bond length, the electrons of the 3p orbitals are paired, which is confirmed by measurement of electron paramagnetic resonance, and magnetic susceptibility and natural bond orbital analysis. The properties of the silicon-silicon π single bond are studied by UV/Vis and Si NMR spectroscopy, and theoretical calculations.
碳 - 碳双键由一个σ键和一个π键组成。最近，在含有碳和杂原子自由基中心的双自由基中提出了π单键的概念，即π键不伴有σ键。在此，我们报道了一种具有硅 - 硅π单键的闭壳化合物。1,2,2,3,4,4 - 六叔丁基双环[1.1.0]四硅烷在桥头硅原子之间存在硅 - 硅π单键。X射线晶体学分析表明，硅 - 硅π单键（2.853(1) Å）远比迄今为止报道的最长硅 - 硅键长得多。尽管键长异常长，但通过电子顺磁共振测量、磁化率和自然键轨道分析证实，3p轨道的电子是成对的。通过紫外/可见光谱和硅核磁共振光谱以及理论计算研究了硅 - 硅π单键的性质。
