Direct comparison of oxygen transfer by iron bleomycin and zinc bleomycin

A direct comparison has been made of the oxygen transfer abilities of Fe(III), Zn(II), and their respective bleomycin (BLM) complexes. These (chelated) metal ions were treated with iodosobenzene in aqueous methanol containing cis or trans-stilbene. It was found that oxygen transfer was observed only when redox active Fe(III).BLM was employed. Benzaldehyde was the only product observed in the above systems in the absence of Fe(III).BLM; the available evidence suggested that it resulted from electron abstraction by iodosobenzene alone. The results of the present study suggest that a metal-oxo intermediate is the species most likely to be involved in oxygen transfer following admixture of Fe(III).BLM and iodosobenzene in the presence of cis-stilbene.