A Stable Four-Membered N-Heterocyclic Carbene

The synthesis of the first four-membered N-heterocyclic carbene is described. Depending on the substituents on the nitrogen atoms, it is possible to characterize at room temperature the carbene dimer or the free carbene. Crystallographic analyses are provided for these carbene species.本文报道了首例四元氮杂环卡宾（four-membered N-heterocyclic carbene）的合成。依据氮原子所连取代基的差异，可在室温下表征该卡宾的二聚体形式或游离态卡宾。针对上述两类卡宾物种，本文均提供了晶体学分析数据。