Metalloporphyrins high valent

J. Bernadou, A. Fabiano, A. Robert, B. Meunier, Redox tautomerism in high-valent metal-oxo-aquo complexes.Origin of the oxygen atom in epoxidation reactions catalyzed by water-soluble metalloporphyrins,/. Am. Chem. Soc. 116 (1994) 9375. 

Warren KD (1977) Ligand Field Theory of f-Orbital Sandwich Complexes. 33 97-137 Warren KD (1976) Ligand Field Theory of Metal Sandwich Complexes. 33 97-137 Watanabe Y, Fujii H (2000) Characterization of High-Valent Oxo-Metalloporphyrins. 97 61-90... 

Watanabe, Y. and H. Fujii (2000). Characterization of high-valent oxo-metalloporphyrins. In B. Meunier (ed.). Structure and Bonding, Vol 97, Springer-Verlag, Berlin, pp. 61-89. 

A number of high-valent metalloporphyrin complexes have been reported. Again high-valency is taken relative to normal species. Many of these species are stabilized by the presence of oxygen donors in the form of oxo or alkoxo ligands. One such set is a series of binuclear p-oxo complexes where the metals (Ru, Os, Mn) have the formal oxidation state +4. All complexes of this class are six-coordinate and include [Ru(0EP)(0H)]20 " [Ru(TPP)(0C6H4CH3)]20 ), [Ru(OEP)C1]20 ),... 

It has been widely accepted that the high-valent iron oxo complex 1 is the active oxidant in metalloporphyrin systems and in non-porphyrin iron complex systems as well. A high-valent iron oxo species can be formed via heterolytic 0-0 bond cleavage of the iron-hydroperoxide 2 or of the iron-peroxyacid species 4 (Figure 5, pathway A). Recently, elegant proof of this heterolytic 0-0 bond cleavage of hydrogen peroxide, MCPBA, and f-butyl hydroperoxide has been provided by Traylor et al in iron porphyrin... 

Two kinds of systems based on Fe(III) or Mn(III) porphyrins are available now for the oxidation of hydrocarbons. The first ones involve such a metalloporphyrin catalyst and an oxygen atom donor like PhIO, H2O2 or O2 and a reducing agent 2-10 They reproduce quite well the reactions catalyzed by cytochrome P450-dependent monooxygenases and involve a high-valent metal-oxo active species which is able to epoxidize alkenes, hydroxylate alkanes and aromatic compounds and perform N- or S- oxidations. 

---