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

Abstract

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 β‐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.