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

Abstract

AbstractPhotochemical activation of nickel‐azido complex 2 [Ni(N3)(PNP)] (PNHP=2,2′‐di(isopropylphosphino)‐4,4′‐ditolylamine) in neat benzene produces diamagnetic complex 3 [Ni(Ph)(PNPNH)], which is crystallographically characterized. DFT calculations support photoinitiated N2‐loss of the azido complex to generate a rare, transient NiIV nitrido species, which bears significant nitridyl radical character. Subsequent trapping of this nitrido through insertion into the NiP bond generates a coordinatively unsaturated NiII 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)(PNPNH)] 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.