Products of [2+2] Cycloaddition between a W Si Triple-bonded Complex and Alkynes: Isolation, Structure, and Non-classical Bonding Interaction

The reactions of a W Si triple-bonded complex, i.e. a silylyne complex, with alkynes gave [2+2] cycloaddition products, which are formally regarded as conjugated metallasilacyclobutadienes. X-ray crystallography and DFT calculations however revealed that the products have a non-planar W-Si-C-C four-membered metallacyclic linkage with a diagonal Si center dot center dot center dot C interaction.