Photochemical nitrogenation of alkanes and arenes by a strongly luminescent osmium(VI) nitrido complex

The search for a highly active nitrido complex that can transfer its nitrogen atom to inert organic molecules remains a challenge to chemists. In this regard, the use of solar energy to generate a reactive nitrido species is an appealing strategy to solve this problem. Here we report the design of a strongly luminescent osmium(VI) nitrido compound, [Os VI (N)( NO 2 -L )(CN) 3 ] − ( NO 2 -OsN ) with emission quantum yield ( Φ ) and life time ( τ ) of 3.0% and 0.48 μs, respectively in dichloromethane solution. Upon irradiation with visible light, this complex readily activates the aliphatic C-H bonds of various hydrocarbons, including alkanes. The excited state of NO 2 -OsN can undergo ring-nitrogenation of arenes, including benzene. Photophysical and computational studies suggest that the excited state of NO 2 -OsN arises from O^N ligand to Os ≡ N charge transfer transitions, and as a result it possesses [Os = N • ] nitridyl character and is highly electrophilic. Activation of C-H bonds through visible light irradiation remains a challenge in attaining energy efficient organic transformations. Here the authors show an osmium(VI) nitrido complex which can perform nitrogenation of cyclic alkanes and arenes by acting as a strong electrophile in the excited state.