Von lithiierten Aminofluorsilanen zu mono- und dimeren Iminosilanen / From Lithiated Aminofluorosilanes to Mono- and Dimeric Iminosilanes

Depending on the solvent and the bulkiness of the substituents, Iithiated aminofluorosilanes are dimers, monomers, or LiF-adducts of iminosilanes. In the crystal structure of the dimeric lithium derivative of di-tert-butyl(rm-butylamino)fluorosilane, each lithium atom is coordinated by one fluorine and two nitrogen atoms. LiF-elimination leads - if sterically possible - to dimerisation. The limits of dimerisation are reached with the dimer diisopropyl(tri-tert-butylphenyI- imino)silane, for which the crystal structure analysis shows severe steric distortions. Fluorine- chlorine-cxchange occurs in reactions of lithiated (tri-tert-butylphenylimino)fluorosilanes with Me 3 SiCl. Iminosilanes are obtained by thermal LiCl-elimination from the resulting salts.