One-Electron Electrochemical Reduction of a Ferrous Porphyrin Dioxygen Complex
Welborn, C.H., David Dolphin, and James, B.R.
J. Am. Chem. Soc.
The O2 complex of ferrous octaethylporphyrin (OEP) [FeII(OEP)L(O2)] was subjected to 1-electron electrochemical reduction to form a product identical to that produced by reacting either FeIIOEP with O2 or FeIIIOEP with O2-. The optical spectrum of the product was rationalized in terms of a 6-coordinate ferrous complex containing a very strong π-acceptor η2-O2 ligand. The ability of an axial ligand to accept heme electrons causes a bathochromic shift of the α-bond which is red-shifted 7 nm with [Fe(OEP)O2]- as compared with Fe(OEP)O2. The weakening and potentially facile cleavage of the O-O bond in this complex is discussed in terms of the reaction mechanisms of cytochrome P 450 and heme oxidase.