Synthesis and structures of some trisorganylstannyl boranes and triorganylstannyl borates

Article abstract of DOI:10.1002/1521-3749(200104)627:4<789::AID-ZAAC789>3.0.CO;2-U

New stannylboranes were prepared from tetramethylpiperidino dichloroborane or B-bromo-pentamethylborazine with lithium triorganylstannides LiSnR₃. Only double stannylation was possible with tmpBCl₂ and LiSnMe₃, while tmpBCl(SnPh₃) was obtained by employing LiSnPh₃. This chloride reacted with LiGePh₃ to the stannyl germyl borane tmpB(GePh₃)(SnPh₃). On the other hand, PhMeNBCl₂ and an excess of LiSnMe₃ gave the borate Li[B(NMePh)(SnMe₃)₃], which was isolated as a solvate with 4 molecules of THF. The compound is present in the solid state as a solvent separated ion pair. The borate Li(H₃BSnMe₃) · 2 THF is dimeric in the solid state. Dimerization occurs via two single Li-H-B bridges and a Li-H(B)-Li bridge. The B-Sn bonds in the borates are practically of the same lengths as those in the boranes. In solution all BH bonds of this trihydridoborate are equivalent. Wiley-VCH Verlag GmbH, 2001.