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 SiO2âperoxo ring as versatile oxo-transfer reagents. However, the latter are elusive species, and have been generated and studied only in argon matrices at â233 °C. Recently, it was demonstrated that unstable silicon species can be isolated by applying the concept of donorâacceptor stabilization. We now report the first synthesis and crystallographic characterization of dioxasiliranes stabilized by N-heterocyclic carbenes that feature a three-membered SiO2âperoxide 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 â Si=O interaction and the shortest Si=O double-bond distance reported to date. Converting dioxygen into more reactive species is extremely useful for direct oxygenation of organic compounds, but doing this with cheap and non-polluting elements is difficult. Now, a carbene-activated silylene has been shown to activate dioxygen, resulting in the isolation of elusive siliconâoxygen species at room temperature.
有机底物氧化的后续步骤涉及使用廉价且环保的
化学元素,而
双氧水活化正是
化学研究的前沿领域。由于
硅是一种无毒且亲氧性强的元素,使用
硅烯可以轻松活化
双氧水,生成具有SiO2-过氧环的二氧
硅烯,作为多功能的氧转移试剂。然而,后者是难以捉摸的物质,仅在
氩气基质中于-233°C生成并研究。最近,通过应用供体-受体稳定概念,证明可以分离不稳定的
硅物质。我们现在报告了首次合成和晶体学表征由N-杂环碳烯稳定化的二氧
硅烯,其具有三成员SiO2-过氧环,可在室温下分离。出乎意料的是,这些物质可以在室温下在
甲苯溶液中进行内部氧转移,生成具有C=O-Si=O相互作用和迄今为止最短Si=O双键距离的独特环状
硅脲络合物。将
双氧水转化为更具反应性的物质对于有机化合物的直接氧化非常有用,但使用廉价且无污染的元素很难做到这一点。现在,碳烯活化的
硅烯已被证明可以活化
双氧水,从而在室温下分离难以捉摸的
硅-氧物质。