Manipulating the Substituent Sphere of a Bicyclic Silicon(I) Ring Compound Results in Anionic Cubane-Type Clusters and a Tetrahedral Silanide

The reaction of the bicyclic silicon(I) ring compound Si₄{N(SiMe₃)Mes}₄ 1 with strong zwitterionic character and moderate sterical demand of the amido substituents with two equivalents of KC₈ was investigated. This resulted in the unexpected abstraction of two amido substituents from 1 and additionally in dimerization to a dianionic Si₈ cluster compound 2 with four unsubstituted silicon atoms and two [K([18]crown-6)]⁺ counter cations. Performing this reaction in the absence of [18]crown-6 results in release of only one amido substituent from 1 and dimerization to a dianionic Si₈ cluster 3 with only two unsubstituted silicon atoms. This reaction with KC₈ was repeated and trapping agents such as SiMe₃Cl and tBuCl were added in-situ whereupon the second isolated homocyclic silylene 4 and a monoanionic hydride and tBu substituted Si₈ cluster 5 with one unsubstituted silicon atom were isolated. Furthermore, 1 was reacted with KOtBu which resulted in the selective abstraction of one SiMe₃ group and formation of the tetrahedral silanide 6 with one imido substituent bridging an edge of the tetrahedron.