Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramakiazaaoba, Aoba-ku, Sendai 980-8578, Japan.
Molecules. 2021 Mar 15;26(6):1632. doi: 10.3390/molecules26061632.
π-Electron systems of silicon have attracted attention because of their narrow HOMO-LUMO gap and high reactivity, but the structural diversity remains limited. Herein, new dialkylboryl-substituted disilenes were synthesized by the selective desilylation-borylation of the corresponding trimethylsilyl-substituted disilenes. The dialkylboryl-substituted disilenes were fully characterized by a combination of NMR spectroscopy, MS spectrometry, single-crystal X-ray diffraction analysis, and theoretical calculations. The longest-wavelength absorption bands of boryldisilenes were bathochromically shifted compared to the corresponding silyl-substituted disilenes, indicating a substantial conjugation between π(Si=Si) and vacant 2p(B) orbitals. In the presence of 4-(dimethylamino)pyridine (DMAP), the dialkylboryl groups in the boryl-substituted disilenes were easily converted to trimethylsilyl groups, suggesting the dialkylboryl-substituted disilenes in the presence of a base serve as the surrogates of disilenyl anions (disilenides).
硅的π-电子体系由于其窄的 HOMO-LUMO 能隙和高反应性而受到关注，但结构多样性仍然有限。在此，通过对相应的三甲基硅基取代二硅烯的选择性去硅基-硼化反应，合成了新的二烷基硼取代二硅烯。通过 NMR 光谱、MS 光谱、单晶 X 射线衍射分析和理论计算的组合，对二烷基硼取代二硅烯进行了充分的表征。与相应的硅取代二硅烯相比，硼取代二硅烯的最长波长吸收带发生了红移，表明π(Si=Si)和空的 2p(B)轨道之间存在显著的共轭。在 4-(二甲氨基)吡啶 (DMAP) 的存在下，硼取代二硅烯中的二烷基硼基很容易转化为三甲基硅基，这表明在碱的存在下，二烷基硼取代二硅烯充当二硅烯阴离子（二硅化物）的替代物。
