Synthesis and Functionalization of Branched Oligosilanes

Bis(trimethylsilyl)methylsilyllithium (1) reacts with HSiCl₃ and MeHSiCl₂ to give 1, 1, 1, 2, 3, 4, 5, 5, 5-nonamethyl-2, 4-bis(trimethylsilyl)silane (2) and tris[bis-(tri-methylsilyl)methylsilyl]silane (3). Bromination of 2 and 3 with CHBr₃ gives the bromosilanes 4 and 5. The reaction of 4 with Na-K alloy yields 1, 2-dimethyl-1, 1, 2, 2-tetrakis[bis(trimethylsilyl)methylsilyl]disilane (6), as a result of reductive coupling. Contrary to 4, bromosilane (5) reacts with Na-K alloy to give a solution of the silylpotassium compound (7). The treatment of 5 in THF with 15 % HCl leads to the formation of chlorotris[bis(trimethylsilyl)methylsilyl]silane (9). The molecular structures of 6 and 9 were established by single-crystal X-ray diffraction analyses.