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

Irradiation of a disphenoidal Ni(II) azido complex, [CztBu(PyriPr)2NiN3] (1), revealed an unprecedented nickel complex, [CztBu(PyriPr)(NH2–PyriPr)] (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, [CztBu(PyriPr)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 CztBu(PyriPr)2Ni (3) and Me3SiN3, suggesting a unique thermal route toward a masked nickel–nitridyl intermediate.