Divergent Radical, Dimerization, and Carbene Formation from One‐Electron Reduction of 2‐Cyanoimidazolium Salts

Abstract Nitriles are indispensable synthetic building blocks for the construction of nitrogen‐containing molecules with broad applications in pharmaceuticals, agrochemicals, and materials science. While their conventional two‐electron reductions enable transformations into amines, carboxylic acids, and aldehydes, their one‐electron reduction pathways, which lead to radical formation, remain largely unexplored. In this study, we report the rational synthesis of 2‐cyanoimidazolium salts and investigate their one‐electron reduction pathways. Upon reduction, these compounds yield both organic radicals and free carbenes. Notably, the free carbene formation occurs via electrophilic cyanide transfer proceeding through a mesoionic carbene (MIC) intermediate. We further demonstrate that the steric bulkiness of imidazolium N‐substituents plays a critical role in determining radical stability. The imidazolium with a sterically bulky substituent generates the persistent radical, which is characterized by electron paramagnetic resonance (EPR) spectroscopy. In contrast, heating the radical with a less bulky N‐substituent leads to dimerization, forming new C(sp)─C(sp 2 ) and C(sp 2 )─N bonds. Insights into their mechanism are supported by density functional theory (DFT) calculations.