Intramolecular C-H Functionalization Followed by a [2σ + 2π] Addition via an Intermediate Nickel-Nitridyl Complex.

Abstract

Irradiation of a disphenoidal Ni(II) azido complex, [Cz tBu(Pyr iPr)2NiN3] (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)2Ni-⃛N•]. Calculations support the generation of an intermediate with significant nitridyl radical character after the loss of N2, which, in turn, undergoes tandem C-H activations, leading to functionalized intermediates and products. This is an unprecedented example of transient Ni-⃛N•-promoted intramolecular C-H functionalization, followed by a [2σ + 2π] addition, yielding bis-metallacyclic product 2. Complex 2 is also observed from the reaction of Ni(I) precursor Cz tBu(Pyr iPr)2Ni (3) and Me3SiN3, suggesting a unique thermal route toward a masked nickel-nitridyl intermediate.