LITHIUM HYDRIDOSILYLAMIDES R-2(H)SIN(LI)R' - PREPARATION, PROPERTIES,AND CRYSTAL-STRUCTURES

The hydridosilylamines R-2(H)SiNHR' (1 a: R=CHMe2, R'=SiMe3; 1b: R=Ph, R'=SiMe3; 1c: R = CMe3, R' = SiMe3; Id: R = R' = CMe3) were prepared by coammonolysis of chlorosilanes R-2(H)SiCl with Me3SiCl (la, Ib) as well as by reaction of (Me3C)(2)(H)SiNHLi with Me3SiCl (le) and Me3CNH Li with (Me3C)(2)(H)SiCl (Id). Treatment of la-ld with n-butyllithium in equimolar ratio in n-hexane resulted in the corresponding lithiumhy dridosilylamides R-2(H)SiN(Li)R' 2a-2d, stable in boiling m-xylene. Th e amines and amides were characterized spectroscopically, and the crys tal structures of 2 b-2 d were determined. The comparison of the Si-H stretching vibrations and Si-29-H-1 coupling constants indicates that the hydrogen atom of the SI-H group in the amides has a high hydride c haracter. The amides are dimeric in the solid state, forming a planar four-membered Li2N2 ring. Strong (Si)H ... Li interactions exist in 2 c and 2 d, may be considered as quasi tricyclic dimers. The ''NSiHLi r ings'' are located on the same side of the central Li2N2 ring. In 2b s ignificant interactions occurs between one lithium atom and the phenyl substituents. Furthermore all three amides show CH3... Li contacts.