Selective Synthesis and Derivatization of Germasilicon Hydrides

Mixed Si/Ge hydrides SixGeyHz are valuable precursors for the deposition of binary Si–Ge
alloys. This work describes the synthesis and full characterization
of the previously unknown germaisotetrasilane Ph3GeSi­(SiH3)3 (2) on a multigram scale from the
reaction of the lithium silanide LiSi­(SiH3)3 with Ph3GeCl. The stability of the Si–Ge bond
in 2 versus electrophiles and nucleophiles has been investigated
with the primary aim of developing new approaches to mixed sila-H-germanes
(H3Ge)xSi­(SiH3)4–x. With 1 equiv of MeLi, 2 reacted cleanly under cleavage of one Si–Si bond to give
Ph3GeSi­(SiH3)2Li, which is a valuable
synthon for further derivatization. In contrast, the dephenylation
reaction of 2 with 1 or 2 equiv of CF3SO3H/iBu2AlH proceeded much less
selectively and afforded the desired Ph/H-germasilanes Ph2HGeSi­(SiH3)3 and PhH2GeSi­(SiH3)3 along with considerable amounts of Si–Ge
scission products.

混合硅/锗氢化物SixGeyHz是用于沉积二元硅锗合金的宝贵前驱体。本工作报道了以硅基锂（lithium silanide, LiSi(SiH3)3）与三苯基氯化锗（Ph3GeCl）为原料，在克级规模下合成此前尚未见报道的锗杂四硅烷Ph3GeSi(SiH3)3（2）并完成全面表征。本研究考察了化合物2中硅锗键对亲电试剂（electrophiles）与亲核试剂（nucleophiles）的稳定性，核心目标为开发制备混合硅氢-锗氢化合物(H3Ge)xSi(SiH3)4–x的新路径。当使用1当量甲基锂（MeLi）时，化合物2通过断裂一条Si-Si键发生专一性反应，生成Ph3GeSi(SiH3)2Li，该产物是可用于进一步衍生化的宝贵合成子（synthon）。与之相反，化合物2与1或2当量三氟甲磺酸（CF3SO3H）/二异丁基氢化铝（iBu2AlH）发生的脱苯基反应选择性显著降低，生成了目标Ph/H-锗硅烷Ph2HGeSi(SiH3)3与PhH2GeSi(SiH3)3，同时伴随大量Si-Ge键断裂副产物。