Silylenes could be attractive for facile dioxygen activation. In a first step dioxasilirane with a SiO₂-peroxo ring is formed, which is a versatile oxo-transfer reagent. This SiO₂-peroxo ring, however, was so far only generated in argon matrices at extremely low temperatures of –233 °C.

Matthias Drieß, professor for chemistry at the Technical University of Berlin, and his team now report the first synthesis and crystallographic characterization of dioxasiliranes at room temperature. The dioxasiliranes were stabilized by N-heterocyclic carbenes that feature a three-membered SiO₂–peroxide ring.

Unexpectedly, these can undergo internal oxygen transfer in toluene solution at ambient temperature to give a unique complex of cyclic sila-urea with C=O → Si=O interaction and the shortest Si=O double-bond distance reported to date.

• From silicon(II)-based dioxygen activation to adducts of elusive dioxasiliranes and sila-ureas stable at room temperature
  Y. Xiong, S. Yao, R. Müller, M. Kaupp, M. Driess,
  Nature Chem. 2010, online.
  DOI: 10.1038/nchem.666