Deoxygenation of Nitrosoarene by N-Heterocyclic Carbene (NHC): Elusive Breslow-type Intermediate Bridging Carbene and Nitrene

N-Heterocyclic carbene (NHC) activates and deoxygenates nitrosoarene (ArNO) to afford arylnitrene (ArN), thereby portraying a fundamental route connecting two 6e− species. A combination of spectroscopic and computational studies suggests that the interaction of ArNO with NHC affords a transient 2,2′-diamino imine-N-oxide as a key intermediate in ArNO deoxygenation.