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)(2)C-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)(2)C=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-center dot](-), 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)(2)C=C(H)SiCl3 (D; 72%) is obtained. Alkyne C undergoes a [4+2]-cycloaddition reaction with 2,3-dimethyl-1,3-butadiene (CH2Cl2, 50 degrees 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 (CH2Cl2, 180 degrees C, 4 d). All closed-shell products were characterized by H-1, C-13{H-1}, and Si-29 NMR spectroscopy; an EPR spectrum of [nBu(4)N][B-center dot] was recorded. The molecular structures of [nBu(4)N][A], [nBu(4)N](2)[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](2-), C, and D are postulated.