Observation of a Photogenerated Rh₂ Nitrenoid Intermediate in C-H Amination

Rh₂-catalyzed C-H amination is a powerful method for nitrogenating organic molecules. While Rh₂ nitrenoids are often invoked as reactive intermediates in these reactions, the exquisite reactivity and fleeting lifetime of these species has precluded their observation. Here, we report the photogeneration of a transient Rh₂ nitrenoid that participates in C-H amination. The developed approach to Rh₂ nitrenoids, based on photochemical cleavage of N-Cl bonds in N-chloroamido ligands, has enabled characterization of a reactive Rh₂ nitrenoid by mass spectrometry and transient absorption spectroscopy. We anticipate that photogeneration of metal nitrenoids will contribute to the development of C-H amination catalysis by providing tools to directly study the structures of these critical intermediates.