Synthesis and Characterization of N-Heterocyclic Carbene-Coordinated Silicon Compounds Bearing a Fused-Ring Bulky Eind Group

The reactions of the fused-ring bulky Eind-substituted 1,2-dibromodisilene, (Eind)BrSi=SiBr(Eind) (1a) (Eind = 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (a)), with N-heterocyclic carbenes (NHCs) (Im-Me₄ = 1,3,4,5-tetramethylimidazol-2-ylidene and Im-ⁱPr₂Me₂ = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) are reported. While the reaction of 1a with the sterically more demanding Im-ⁱPr₂Me₂ led to the formation of the mono-NHC adduct of arylbromosilylene, (Im-ⁱPr₂Me₂)→SiBr(Eind) (2a′), a similar reaction using the less bulky Im-Me₄ affords the bis-NHC adduct of formal arylsilyliumylidene cation, [(Im-Me₄)₂→Si(Eind)]⁺[Br⁻] (3a). The NHC adducts 2a′ and 3a can also be prepared by the dehydrobromination of Eind-substituted dibromohydrosilane, (Eind)SiHBr₂ (4a), with NHCs. The NHC-coordinated silicon compounds have been characterized by spectroscopic methods. The molecular structures of bis-NHC adduct, [(Im-ⁱPr₂Me₂)₂→Si(Eind)]⁺[Br⁻] (3a′), and 4a have been determined by X-ray crystallography. View Full-Text