Exhaustively Trichlorosilylated C1 and C2 Building Blocks: Beyond the Müller–Rochow Direct Process

The Cl–-induced heterolysis of the Si–Si bond in Si2Cl6 generates an [SiCl3]− ion as reactive intermediate. When carried out in the presence of CCl4 or Cl2C═CCl2 (CH2Cl2 solutions, room temperature or below), the reaction furnishes the monocarbanion [C(SiCl3)3]− ([A]−; 92%) or the vicinal dianion [(Cl3Si)2C–C(SiCl3)2]2– ([B]2–; 85%) in excellent yields. Starting from [B]2–, the tetrasilylethane (Cl3Si)2(H)C–C(H)(SiCl3)2 (H2B) and the tetrasilylethene (Cl3Si)2C═C(SiCl3)2 (B; 96%) are readily available through protonation (CF3SO3H) or oxidation (CuCl2), respectively. Equimolar mixtures of H2B/[B]2– or B/[B]2– 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 CuCl2 furnishes the disilylethyne Cl3SiC≡CSiCl3 (C; 80%); in the presence of [HMe3N]Cl, the trisilylethene (Cl3Si)2C═C(H)SiCl3 (D; 72%) is obtained. Alkyne C undergoes a [4+2]-cycloaddition reaction with 2,3-dimethyl-1,3-butadiene (CH2Cl2, 50 °C, 3d) and t...