[Bu₄P]⁺Cl⁻-Catalyzed Reactions of Trichlorosilane and Dichloromethylsilane with Vinyltrichlorosilane: New Synthetic Method for 1,1,4,4-Tetrachloro-2,5-bis(trichlorosilyl)-1,4-disilacyclohexane Compounds

[Bu4P]+Cl−-catalyzed reactions of trichlorosilane and dichloromethylsilane with vinyltrichlorosilane gave 1,1,4,4-tetrachloro-2,5-bis(trichlorosilyl)-1,4-disilacyclohexane (1) and 1,1,4,4-tetrachloro-2,5-bis(methyldichlorosilyl)-1,4-disilacyclohexane (4), respectively.