Late, first-row transition metal nitrenoid complexes have received great attention as viable and cost-effective nitrene group transfer reagents. Co(III) imido complexes, however, have been relatively less explored in the field of C–H amination since the majority of these complexes feature low-spin electronic configurations, resulting in remarkably unreactive species. To overcome this limitation, we employed a weak field dipyrromethene ligand to prepare a Co(III) imido complex displaying a unique open-shell electronic configuration accessed via thermal spin-transition. The presence of unpaired electron density along the Co–N multiple bond renders this species highly reactive. Consequently, the Co(III) imido is capable of catalytic intramolecular C–H amination. This is the first example of catalytic C–H amination from a structurally characterized Co(III) imido complex, emphasizing how the open-shell electronic structure plays a key role in facilitating C–H functionalization. Furthermore, additional synthetic parameters such as imido geometry, molecular oxidation state, and identity of the nitrene substituents were engineered to investigate essential attributes for C–H amination.

Manipulation of electronic and physical structure of cobalt nitrenoid complexes for C−H amination

ACS Fall 2021

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