PREPARATION AND STRUCTURAL CHARACTERIZATION OF NEW DERIVATIVES OF DIGERMANE BEARING TRIS(TRIMETHYLSILYL)SILYL SUBSTITUENTS

The reaction of GeCl4 with 2 equiv of (THF)3LiSi(SiMe3)3 affords the unusual digermane derivative [(Me3Si)3SiGeCl2]2 instead of the expected disubstituted monogermane dichloride. In addition to characterization by elemental analyses and NMR spectra (H-1, C-13, and Si-29), the molecular formula of the digermane was determined by field desorption mass spectra, which indicated the presence of a Ge-Ge bond in the structure. An X-ray crystal structure determination revealed extensive disorder in the solid-state arrangement; the structure of the digermanium core was determined by holding the geometry of the Si(Si(CH3)3)3 groups fixed. Crystals of [(Me3Si)3SiGeCl2]2 were cubic, Pa3BAR, with a = 16.103 (2) angstrom, V = 4176 angstrom 3, and Z = 4. Also prepared were two organo derivatives [(Me3Si)3SeGeR2]2 (R = CH3, C6H5) that, according to their NMR spectra, appear to have the same digermane structure. All the digermane products are unreactive toward atmospheric moisture.