A Stable Silylene with a σ², π- Butadiene Ligand

The synthesis of a new type of silylene 1 is reported. It adopts a bicyclo[2.1.1]hexene structure in which a hafnocene group is incorporated. The silylene is stabilized by homoconjugation with the remote C═C double bond. This is indicated by its highly shielded 29Si NMR chemical shift (δ29Si = −155) and is firmly established by its experimental molecular structure from XRD analysis. The results of a detailed bonding analysis based on DFT...