Key points are not available for this paper at this time.
The environment of the CuI ion in the distal ligand group decides the fate of the reduction of O2 by the two analogues 1 and 2 of the heme a3 CuB center in cytochrome c oxidase. The fourfold coordination by N in 1 favors the CuII oxidation state and leads to a 4 e−–4 H+ reduction and the formation of H2O under physiological conditions, while with 2 a 2 e−–2 H+ reduction occurs to form the cytotoxic H2O2.
Collman et al. (1998) studied this question.