Route Si6 revisited

Starting from 1,4-dipotassiotetrasilane 1,1,4,4-tetrakis(trimethylsilyl)octamethylcyclohexasilane can easily be obtained. This can be used to generate trans-1,4-dipotassiocyclohexasilane. Transmetallation with magnesium leads to a formal inversion of configuration at one of the anionic silicon atoms. Depending on the stereochemical configuration of the starting material hydrolyses give either the trans- or cis-1,4-dihydrocyclohexasilanes. The 1,4-dipotassiocyclohexasilane also provides a convenient precursor for the synthesis of [2.2.0], [2.2.1] and [2.2.2] bicyclo oligosilane systems. The principal possibility of further functionalization of the cage molecules is demonstrated by the synthesis and derivatization of 1,4-dipotassio-[2.2.2]-bicyclooctasilane. The extraordinary selectivity for the cleavage of trimethylsilyl groups is demonstrated for the case of bis(trimethylsilyl)bis(undecamethylcyclohexasilanyl)silane, where in a molecule which contains 16 silicon–silicon bonds, a trimethylsilyl group is selectively attacked.