Beiträge zur Chemie des Bors, 124 [1] Tris(trimethylsilyl)silyl-borane und Tris(trimethylsilyl)silyl-borate / Contributions to the Chemistry of Boron, 124 [1] Tris(trimethylsilyl)silyl Boranes and Tris(trimethylsilyl)silyl Borates

The reactions of several boron halides, methoxides, alkyls and hydrides with tris(tri-methylsilyl)silyllithium, which was isolated as the solvate [(CH₃)₃Si]₃SiLi · ₃C₄H₈O, 1(TMSSLi) have been studied. (CH₃)₂B−Si[Si(CH₃)₃]₃ and 9−[(CH₃)₃Si]₃Si-9-BBN, were isolated, while [(CH₃)₃Si]₃Si-B(ᵗC₄H₉)₂ could only be detected by ¹¹B NMR. In addition TMSS-B[N(CH₃)₂]₂, (TMSS)₂BNMe₂ and (TMSS)₂BOCH₃ were prepared. The methoxy-boranes (CH₃)₃₋ₙB(OCH₃)ₙ add to 1 forming silylborates; however, no OCH₃/Si[Si(CH₃)₃]₃ substitution occurs. The hydrogen bridge in 9-BBN is cleaved symmetrically. The results can be explained by the basicity and the steric requirements of the TMSS group. The TMSS group exhibits a deshielding effect at the boron nucleus relative to the (CH₃)₃Si group for silylboranes as well as for silylborates.