Georg Isabelle, Teichmann Julian, Bursch Markus, Tillmann Jan, Endeward Burkhard, Bolte Michael, Lerner Hans-Wolfram, Grimme Stefan, Wagner Matthias
Mulliken Center for Theoretical Chemistry , Institut für Physikalische und Theoretische Chemie, Universität Bonn , Beringstrasse 4 , Bonn 53115 , Germany.
J Am Chem Soc. 2018 Aug 1;140(30):9696-9708. doi: 10.1021/jacs.8b05950. Epub 2018 Jul 23.
The Cl-induced heterolysis of the Si-Si bond in SiCl generates an [SiCl] ion as reactive intermediate. When carried out in the presence of CCl or ClC═CCl (CHCl solutions, room temperature or below), the reaction furnishes the monocarbanion [C(SiCl)] ([A]; 92%) or the vicinal dianion [(ClSi)C-C(SiCl)] ([B]; 85%) in excellent yields. Starting from [B], the tetrasilylethane (ClSi)(H)C-C(H)(SiCl) (HB) and the tetrasilylethene (ClSi)C═C(SiCl) (B; 96%) are readily available through protonation (CFSOH) or oxidation (CuCl), respectively. Equimolar mixtures of HB/[B] or B/[B] quantitatively produce 2 equiv of the monoanion [HB] or the blue radical anion [B], respectively. Treatment of B with Cl ions in the presence of CuCl furnishes the disilylethyne ClSiC≡CSiCl (C; 80%); in the presence of [HMeN]Cl, the trisilylethene (ClSi)C═C(H)SiCl (D; 72%) is obtained. Alkyne C undergoes a [4+2]-cycloaddition reaction with 2,3-dimethyl-1,3-butadiene (CHCl, 50 °C, 3d) and thus provides access to 1,2-bis(trichlorosilyl)-4,5-dimethylbenzene (E1; 80%) after oxidation with DDQ. The corresponding 1,2-bis(trichlorosilyl)-3,4,5,6-tetraphenylbenzene (E2; 83%) was prepared from C and 2,3,4,5-tetraphenyl-2,4-cyclopentadien-1-one under CO extrusion at elevated temperatures (CHCl, 180 °C, 4 d). All closed-shell products were characterized by H, C{H}, and Si NMR spectroscopy; an EPR spectrum of [ nBuN][B] was recorded. The molecular structures of [ nBuN][A], [ nBuN][B], B, E1, and E2 were further confirmed by single-crystal X-ray diffraction. On the basis of detailed experimental investigations, augmented by quantum-chemical calculations, plausible reaction mechanisms for the formation of [A], [B], C, and D are postulated.
SiCl中Si-Si键的Cl诱导异裂产生[SiCl]离子作为反应中间体。在CCl或ClC═CCl（CHCl溶液，室温或更低温度）存在下进行反应时，反应以优异的产率提供单碳负离子[C(SiCl)]（[A]；92%）或邻位双负离子[(ClSi)C-C(SiCl)]（[B]；85%）。从[B]开始，通过质子化（CFSOH）或氧化（CuCl）分别容易得到四硅乙烷(ClSi)(H)C-C(H)(SiCl)（HB）和四硅乙烯(ClSi)C═C(SiCl)（B；96%）。HB/[B]或B/[B]的等摩尔混合物分别定量生成2当量的单负离子[HB]或蓝色自由基负离子[B]。在CuCl存在下用Cl离子处理B得到二硅乙炔ClSiC≡CSiCl（C；80%）；在[HMeN]Cl存在下，得到三硅乙烯(ClSi)C═C(H)SiCl（D；72%）。炔烃C与2,3-二甲基-1,3-丁二烯发生[4+2]环加成反应（CHCl，50℃，3天），经DDQ氧化后得到1,2-双（三氯硅基）-4,5-二甲基苯（E1；80%）。相应的1,2-双（三氯硅基）-3,4,5,6-四苯基苯（E2；83%）由C和2,3,4,5-四苯基-2,4-环戊二烯-1-酮在高温下经CO挤出反应制备（CHCl，180℃，4天）。所有闭壳产物均通过1H、13C{1H}和29Si NMR光谱进行表征；记录了[nBuN][B]的EPR光谱。[nBuN][A]、[nBuN][B]、B、E1和E2的分子结构通过单晶X射线衍射进一步确认。在详细实验研究的基础上，结合量子化学计算，推测了[A]、[B]、C和D形成的合理反应机理。
