PHOTOCHEMICAL AND THERMAL BROMINATION OF METAL ACETYLACETONATES BY PYRIDINIUM BROMOCHROMATE IN ACETIC-ACID MEDIUM

Photochemical and thermal brominations of metal beta-diketonate comple xes of Mn(II), Co(II), Cu(II), Zn(II), Cr(III), Mn(III), Fe(III), Co(I II), Ce(IV). Th(IV) and UO2(VI) by pyridinium bromochromate (PBC) in g lacial acetic acid have been carried out. Under ambient conditions, th e tris and tetrakis chelates underwent electrophilic gamma-bromination whereas the bis-chelates decomposed yielding bromo complexes by nucle ophilic addition of bromine. Under photo irradiation lambda = 254 or l ambda = 357 nm except those of Cr(III), Ce(IV) and Th(IV) complexes wh ich underwent electrophilic gamma-substitution, all the other complexe s decomposed forming bromo complexes.