Over the last three decades, the highly tunable properties of N-heterocyclic carbenes (NHCs) and other stable singlet carbenes have led to a variety of applications. This perspective shows a novel facet of carbenes—i.e., their reductive properties—that allows them to function as catalysts in single-electron transfer (SET) reactions. The isolation and even the spectroscopic characterization of a singly oxidized carbene have yet to be done, but these species readily abstract hydrogen atoms while giving back the carbene conjugate acid, which behaves as the resting state of catalytic cycles. In sharp contrast, a doubly oxidized carbene has been isolated, and there is a strong likelihood that many other carbene dications will be isolated. Their first Lewis acidity is very high, suggesting possible applications in Lewis acid catalysis.

中文翻译：

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单氧化和双氧化卡宾及其在催化中的应用


在过去的三十年里，N-杂环卡宾 （NHC） 和其他稳定的单线态卡宾的高度可调特性导致了各种应用。该视角显示了卡宾的一个新方面，即它们的还原特性，使它们能够在单电子转移 （SET） 反应中充当催化剂。单氧化卡宾的分离甚至光谱表征尚未完成，但这些物质很容易提取氢原子，同时返回卡宾共轭酸，其表现为催化循环的静止状态。与此形成鲜明对比的是，已经分离出一种双重氧化的卡宾，并且很有可能分离出许多其他卡宾化合物。他们的第一个路易斯酸度非常高，表明可能在路易斯酸催化中应用。