title: From silicon(II)-based dioxygen activation to adducts of elusive dioxasiliranes and sila-ureas stable at room temperature.
abstract: Dioxygen activation for the subsequent oxygenation of organic substrates that involves cheap and environmentally friendly chemical elements is at the cutting edge of chemical research. As silicon is a non-toxic and highly oxophilic element, the use of silylenes could be attractive for facile dioxygen activation to give dioxasiliranes with a SiO(2)-peroxo ring as versatile oxo-transfer reagents. However, the latter are elusive species, and have been generated and studied only in argon matrices at -233 degrees C. Recently, it was demonstrated that unstable silicon species can be isolated by applying the concept of donor-acceptor stabilization. We now report the first synthesis and crystallographic characterization of dioxasiliranes stabilized by N-heterocyclic carbenes that feature a three-membered SiO(2)-peroxide ring, isolable at room temperature. 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.
authors.affiliation: Institute of Chemistry: Metalorganics and Inorganic Materials, Technische Universität Berlin, Strasse des 17. Juni 135, Sekr. C2, D-10623 Berlin, Germany.
authors.forename: Yun
authors.initials: Y
authors.lastname: Xiong
authors.forename: Shenglai
authors.initials: S
authors.lastname: Yao
authors.forename: Robert
authors.initials: R
authors.lastname: Müller
authors.forename: Martin
authors.initials: M
authors.lastname: Kaupp
authors.forename: Matthias
authors.initials: M
authors.lastname: Driess
mesh_terms: D018360:Crystallography, X-Ray; D008697:Methane / Q000031:analogs & derivatives / Q000737:chemistry; D008968:Molecular Conformation; D010100:Oxygen / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013696:Temperature; D014508:Urea / Q000737:chemistry*
chemical_list: D012821:Silanes; C030011:carbene; D014508:Urea; D008697:Methane; D010100:Oxygen; D012825:Silicon