Trimethylblei-Lithium in Tetrahydrofuran: Synthese von Trimethyl(trimethylplumbyl)silan und des Trimethylplumbyltrihydridoborat-Anions / Trimethyllead-Lithium in Tetrahydrofuran: Synthesis of Trimethyl(trimethylplumbyl)silane and of the Trimethylplumbyltrihydridoborate Anion

Solutions of trimethyllead-lithium, [Me Pb]Li (1), in tetrahydrofuran (THF) (-0.5 M) can be obtained from trimethyllead bromide and an excess of lithium at –78°C. H. C and Pb NMR are used for monitoring the formation of the reagent. Extensive decomposition into lead and tetramethyllead is observed at –20°C within minutes. The application of this reagent is demonstrated by the synthesis of trimethyl(trimethylplumbyl)silane (2) and by its stoichiometric 1:1 reaction with BH –THF at –78°C, leading to lithium trimethylplumbyltrihydridoborate [Me PB–BH ]Li (3). The composition of the products in solution follows conclusively from their H, C, B, C, Si, and Pb NMR data. The silane 2 decomposes slowly at ambient temperature into Me Si, Me Pb and lead. The borate is even less stable, decomposing at temperatures above –30°C mainly into lead, Me Pb, [H B]Li and [Me B]Li.