The reaction of NOBF4 with antimony(III) corroles: Fluoride binding to antimony and regioselective nitration of the macrocycle

The reaction of antimony(III) corroles with nitrosonium tetrafluoroborate in the presence of air led to trans-difluoroantimony(V) 3,17-dinitro-corrole complexes. A trans-dinitrosylantimony(V) corrole compound has been proposed as a possible reaction intermediate that is subsequently converted into a trans-dinitroantimony(V) corrole product. The formation of these intermediate species has been established via in situ FT-IR spectra. This trans-dinitroantimony(V) corrole species can transfer the nitro group to the beta-pyrrole positions (C3 and C17) of the corrole periphery via a radical pathway. The binding of fluoride to the axial positions of antimony(V) corrole occurs via nucleophilic attack of fluoride ion from BF4-. The trans-difluoroantimony(V) 3,17-dinitro-corrole complexes are fully characterized via X-ray crystallography, UV-vis, FT-IR, and NMR spectroscopy. They catalyze oxygenation reactions under photo-redox conditions in presence of air and light at ambient temperature by forming singlet oxygen.

Automated summary

The reaction of antimony(III) corroles with nitrosonium tetrafluoroborate in the presence of air led to the formation of trans-difluoroantimony(V) 3,17-dinitro-corrole complexes. The formation of these complexes involves a possible intermediate trans-dinitrosylantimony(V) corrole compound. In situ FT-IR spectra confirmed the presence of these intermediate species. The trans-difluoroantimony(V) 3,17-dinitro-corrole complexes, characterized by various spectroscopic techniques, can catalyze oxygenation reactions by forming singlet oxygen under photo-redox conditions in the presence of air and light at ambient temperature.