THE X-RAY CRYSTAL-STRUCTURES OF THE MONONUCLEAR SILYLLITHIUM SPECIES LI(THF)(3)SIPH(3) AND LI(THF)(3)SI(SIME(3))(3)

The organosilyllithium tetrahydrofuranate complexes Li(THF)(3)SiPh(3) (1) and Li(THF)(3)Si(SiMe(3))(2) (2) were crystallized and structurall y characterized by X-ray crystallography. Both compounds possess monom eric structures with relatively long (ca. 2.67 Angstrom) Li-Si bonds. In addition, the lithium-bound silicons have distorted tetrahedral geo metries with low C-Si-C and Si-Si-Si angles of 101.3 degrees (av.) (1) and 102.6 degrees (av.) (2). Compound 1, which has not been reported as an isolated species, has been characterized by H-1,Li-7, Si-29 NMR and IR spectroscopy. These studies indicate that the Li-Si bond remain s intact in THF solution at -80 degrees C.