Intramolecular C-H Functionalization Followed By A [2 Sigma+2 Pi]-Addition Via An Intermediate Nickel-Nitridyl Complex

Irradiation of a disphenoidal Ni(II) azido complex, [Cz(tBu)(Pyr(iPr))(2)NiN3] (1), revealed an unprecedented nickel complex, [Cz(tBu)(Pyr(iPr))(NH2-Pyr(iPr))] (2), in >90% isolated yield. As evidenced by single-crystal X-ray diffraction, 2 is produced by double intramolecular C-H activation of a putative nickel_nitridyl intermediate, [Cz(tBu)(Pyr(iPr))(2)Ni(sic)N-center dot]. Calculations support the generation of an intermediate with significant nitridyl radical character after the loss of N-2, which, in turn, undergoes tandem C-H activations, leading to functionalized intermediates and products. This is an unprecedented example of transient Ni(sic)N-center dot-promoted intramolecular C-H functionalization, followed by a [2(sigma) + 2(pi)] addition, yielding bis-metallacyclic product 2. Complex 2 is also observed from the reaction of Ni(I) precursor Cz(tBu)(Pyr(iPr))(2)Ni (3) and Me3SiN3, suggesting a unique thermal route toward a masked nickel-nitridyl intermediate.