Silaethen

Directed Gas Phase Formation of Silene (H2 SiCH2 )

The silene molecule (H₂ SiCH₂ ; X¹ A₁ ) has been synthesized under single collision conditions via the bimolecular gas phase reaction of ground state methylidyne radicals (CH) with silane (SiH₄ ). Exploiting crossed molecular beams experiments augmented by high-level electronic structure calculations, the elementary reaction commenced on the doublet surface through a barrierless insertion of the methylidyne radical into a silicon-hydrogen bond forming the silylmethyl (CH₂ SiH₃ ; X² A') complex followed by hydrogen migration to the methylsilyl radical (SiH₂ CH₃ ; X² A'). Both silylmethyl and methylsilyl intermediates undergo unimolecular hydrogen loss to silene (H₂ SiCH₂ ; X¹ A₁ ). The exploration of the elementary reaction of methylidyne with silane delivers a unique view at the widely uncharted reaction dynamics and isomerization processes of the carbon-silicon system in the gas phase, which are noticeably different from those of the isovalent carbon system thus contributing to our knowledge on carbon silicon bond couplings at the molecular level.

Silylenes, Silenes, and Disilenes: Novel Silicon-Based Reagents for Organic Synthesis?

Silylenes, silenes, and disilenes are silicon analogues of carbenes and alkenes. Since the first detection and isolation of these species a few decades ago, focus has been given to their fundamental structure and reactivity properties. Recent developments show that the time is set to exploit their unique chemistry in applied areas. Emerging applications in catalysis and stereoselective synthesis point to a new field within synthetic organosilicon chemistry.