Mechanistic snapshots of rhodium-catalyzed acylnitrene transfer reactions

Rhodium (Rh) acylnitrene complexes are widely implicated in catalytic C-H amidation reactions but have eluded isolation and structural characterization. To overcome this challenge, we designed a chromophoric octahedral Rh complex with a bidentate dioxazolone ligand, in which photoinduced metal-to-ligand charge transfer initiates catalytic C-H amidation. X-ray photocrystallographic analysis of the Rh-dioxazolone complex allowed structural elucidation of the targeted Rh-acylnitrenoid and provided firm evidence that the singlet nitrenoid species is primarily responsible for acylamino transfer reactions. We also monitored in crystallo reaction of a nucleophile with the in situ-generated Rh-acylnitrenoid, which provided a crystallographically traceable reaction system to capture mechanistic snapshots of nitrenoid transfer.

Automated summary

To overcome the challenge of isolating and characterizing Rhodium (Rh) acylnitrene complexes, a chromophoric octahedral Rh complex with a bidentate dioxazolone ligand was designed. X-ray photocrystallographic analysis allowed structural elucidation of the Rh-acylnitrenoid and provided evidence that the singlet nitrenoid species is responsible for acylamino transfer reactions. In-crystallo reaction of a nucleophile with the in-situ-generated Rh-acylnitrenoid provided a traceable reaction system to capture mechanistic snapshots of nitrenoid transfer.