Photochemical and thermal bromination of metal acetylacetonates by pyridinium bromochromate in acetic acid medium

Abstract

Photochemical and thermal brominations of metal β-diketonate complexes of Mn(II), Co(II), Cu(II), Zn(II), Cr(III), Mn(III), Fe(III), Co(III), Ce(IV), Th(IV) and UO₂(VI) by pyridinium bromochromate (PBe) in glacial acetic acid have been carried out. Under ambient conditions, the tris and tetrakis chelates underwent electrophilic γ-bromination whereas the bis-chelates decomposed yielding bromo complexes by nucleophilic addition of bromine. Under photo irradiation λ = 254 or λ = 357 nm except those of Cr(III), Ce(IV) and Th(IV) complexes which underwent electrophilic λ-substitution, all the other complexes decomposed forming bromo complexes.