Models of oxidized heme proteins. Preparation and characterization of a trans-dioxoruthe nium(VI) porphyrin complex

High-valent iron porphyrin complexes have been suggested for the oxidized states of the peroxidases, 1 and similar intermediates have been implicated in the oxygen-transfer reactions of cytochrome P-450² and the dioxygen reduction of cytochrome oxidase.³ An understanding of the redox chemistry mediated by these enzymes has been hampered by the install bility of these oxidized iron-heme intermediates and by the lack of simple chemical models for these reactive states. Synthetic examples of an oxoiron(IV) prophryin⁴ and an oxoiron(IV) porphyrin cation radical⁵ are now known; however, the thermal instability of each has prevented their isolation as pure solids. The periodic relationship of iron and ruthenium suggests that the latter could provide stable examples of oxidized metalloporphyrins.