CH Activation of Benzene by a Photoactivated Ni II (azide): Formation of a Transient Nickel Nitrido Complex

Abstract

Photochemical activation of nickel‐azido complex 2 [Ni(N 3 )(PNP)] (PN H P=2,2′‐di(isopropylphosphino)‐4,4′‐ditolylamine) in neat benzene produces diamagnetic complex 3 [Ni(Ph)(PN P N H )], which is crystallographically characterized. DFT calculations support photoinitiated N 2 ‐loss of the azido complex to generate a rare, transient Ni IV nitrido species, which bears significant nitridyl radical character. Subsequent trapping of this nitrido through insertion into the NiP bond generates a coordinatively unsaturated Ni II imidophosphorane PN donor. This species shows unprecedented reactivity toward 1,2‐addition of a CH bond of benzene to form 3 . The structurally characterized chlorido complex 4 [Ni(Cl)(PN P N H )] is generated by reaction of 3 with HCl or by direct photolysis of 2 in chlorobenzene. This is the first report of aromatic CH bond activation by a trapped transient nitrido species of a late transition metal.