Mechanism of autoxidation of iron(II) porphyrins. Detection of a peroxo-bridged iron(III) porphyrin dimer and the mechanism of its thermal decomposition to the oxo-bridged iron(III) porphyrin dimer

Abstract

Anhand sichtbarer und 1H‐NMR‐ spektroskopischer Untersuchungen wird die Bildung eines neuen Intermediärprodukts bei der Zugabe von Disauerstoff zu Toluollösungen von FeL bei ‐80°C nachgewiesen.

Oxygen Activation Chemistry of Pacman and Hangman Porphyrin Architectures Based on Xanthene and Dibenzofuran Spacers

“…24). Reaction of two ferrous porphyrin subunits with O 2 re-forms the diiron(III)-m-oxo assembly via a Balch-type mechanism (164,165) for reentry into the oxidative process. In this way, a photocycle for organic substrate oxidation can be constructed using molecular oxygen as the terminal oxidant and oxygen atom source.…”

Oxidative Polymerization of Pyrrole Promoted by Four-Electron Transfer to O2: Catalysis of O2-Oxidation byμ-Oxo Dinuclear Complexes with Macrocyclic Ligands

“…The redox potential of 1 is significantly higher than those of the l-oxo dinuclear metalloporphyrins measured under the same conditions (E f (V vs Ag/ AgCl): 2, 0.38 [34] ; 3, 0.51 [34] ; 4, a -0.09 [29] ). On the other hand, it has been reported [44,45] that [(pc)Fe II ] is almost quantitatively oxidized by O 2 to 1 without the formation of partially reduced oxygen species such as H 2 O 2 . Indeed, our previous study on the electrochemical reduction of O 2 catalyzed by [(pc)Fe] adsorbed at an electrode surface revealed [33] that most of O 2 molecules (84%) are reduced by four electrons into H 2 O.…”

“…Autoxidation of the mononuclear iron(II) complex to the corresponding l-oxo diiron(III) complexes [44,45] requires a high concentration of the catalyst because of the decrease in molecularity. However, a large turnover value (A 1 000) is obtained for 1 for a prolonged polymerization period (Table 1), which is much higher than the previously reported polymerization of pyrrole using the conventional catalytic systems: [(salen)VOV(salen)][BF 4 ] 2 1CF 3 SO 3 H, 61; [24] CuCl1AlCl 3 1O 2 , 13; [21] FeCl 3 N 6 H 2 O1O 2 , 30; [22] VO(acac) 2 -AlCl 3 1O 2 , 2.6.…”

The Radical Versus Non-radical Reactive Intermediates in the Iron(III) Porphyrin Catalyzed Oxidation Reactions by Hydroperoxides, Hydrogen Peroxide and Iodosylarene

“…This proposition is supported by our observation that the spectrum of 1 remained unchanged in presence of dioxygen, when product formation was continued and more than 100% (with respect to the t-BuOOH used) of the ketone was formed under dioxygen. The stability of similar oxo-iron(IV) porphyrin species in presence of dioxygen is not very surprising [28]. We believe that 1 atm of dioxygen is not sufficient enough to trap all the alkoxy radicals formed via Eq.…”