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 Si{N(SiMe)Mes} 1 with strong zwitterionic character and moderate sterical demand of the amido substituents with two equivalents of KC was investigated. This resulted in the unexpected abstraction of two amido substituents from 1 and additionally in dimerization to a dianionic Si 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 Si cluster 3 with only two unsubstituted silicon atoms.

Silicon Chalcogenide Cage Compounds: New Structures Derived from the Bicyclic Silicon(I) Ring Compound Si {N(SiMe )Mes}.

The bicyclic silicon(I) ring compound Si {N(SiMe )Mes} (2) was used as starting material in reactions with chalcogens and chalcogen transfer agents at low temperatures. This resulted in the selective formation of new cage compounds. With Me NO, a silicon oxide with adamantane-type cage 3 was isolated that represents the first isolated T silsesquioxane.

Reactivity of the Bicyclic Amido-Substituted Silicon(I) Ring Compound Si {N(SiMe )Mes} with FLP-Type Character.

The bicyclic amido-substituted silicon(I) ring compound Si {N(SiMe )Mes} 2 (Mes=Mesityl=2,4,6-Me C H ) features enhanced zwitterionic character and different reactivity from the analogous compound Si {N(SiMe )Dipp} 1 (Dipp=2,6- Pr C H ) due to the smaller mesityl substituents. In a reaction with the N-heterocyclic carbene NHC (1,3,4,5-tetramethyl-imidazol-2-ylidene), we observe adduct formation to give Si {N(SiMe )Mes}  ⋅ NHC (3). This adduct reacts further with the Lewis acid BH to yield the Lewis acid-base complex Si {N(SiMe )Mes}  ⋅ NHC  ⋅ BH (4).