DNA cleavage by a series of nonheme iron complexes supported by pentadentate carboxamido ligands, dpaq(R) (R = OMe, H, Cl, and NO2), was evaluated in the presence of a reducing agent under air and in the presence of hydrogen peroxide. Cleavage efficiency clearly increased as redox potential became more positive. These results provide an opportunity for the designing of Bleomycin mimics with higher activity.