Cytochrome c oxidase models. Dinuclear iron/copper complexes derived from covalently modified deuteroporphyrins

The deuterohemin complex obtained by covalent modification of the propionic acid side chains of the porphyrin with a glycyl-L-histidine methyl ester residue and a bis(benzimidazole) residue, respectively, is reported. The bis(benzimidazole) arm can be used as a ligand for a copper(II) ion, giving an heterodinuclear complex that mimics the dioxygen reduction center found in cytochrome c oxidase. The relevance of the present model system is shown by the smooth reactivity that the reduced form of the heme/copper complex exhibits to dioxygen. The reaction, in fact, proceeds nondestructively even at room temperature to give the fully oxidized Fe(III)/Cu(II) species.