Oxygen iron dioxygen adduct

Proniewicz LM, Paeng IR, Nakamoto K. 1991. Resonance raman spectra of two isomeric dioxygen adducts of iron(II) porphyrins and rr-cation radical and nonradical oxoferryl porphyrins produced in dioxygen matrixes Simultaneous observation of more than seven oxygen isotope sensitive bands J Am Chem Soc 113 3294. 

Iron(II) meso-tetrakis(2,4,6-trimethoxyphenyl)porphyrin and the triethoxy analogue have been synthesized by Vaska. These are different to the capped and picket fence porphyrins in that both sides of the porphyrin are sterically hindered. Dioxygen uptake by these iron(II) porphyrins at 25 °C in solution was found to be partially reversible. La Mar and co-workers166 have shown that the porphyrins Fe[T(2,4,6-OMe)3PP], Fe[T(2,4,6-OEt)3PP] and Fe[TpivPP] take up oxygen at low temperatures, in the absence of a base such as Melm or pyridine, to give dioxygen adducts of the... 

Fig. 21. Typical intermediates in hemoprotein enzyme active sites. The iron protoporphyrin IX cofactor (heme) forms dioxygen adducts termed oxy-species. In the course of oxygen activation and catalytic redox transformations, the oxy form can be consecutively converted into hydroperoxo- and oxo-type intermediates, which are usually referred to as compound 0, compound I, and compound II. Reproduced with permission from Ref (183). Copyright Nature Publishing Group.

In contrast to iron and cobalt, end-on superoxo-copper(II) species do not dominate the field of copper-oxygen chemistry. In 1 1 copper-dioxygen adducts, an alternative side-on, t 2 coordination mode is sometimes observed these [(L)Cu11 (t 2-(02 ")] or [(L)Cum-(ri2-(022 )] complexes are discussed below. Mononuclear copper-dioxygen complexes easily react with the second molecule of the Cu(I) complex, forming peroxo- or dioxo-bridged dinuclear species (Section 4.4). For sterically unhindered... 

The syntheses of two complexes are described here the cobalt(II) lacunar cyclidene complex in which R =—(CH2)e— and = R = —CH3, and the iron(II) complex in which R =m-xylylene, R = —CH2C6H5, and R = —CgHs- The former is the most studied example of a lacunar cyclidene oxygen carrier, and the latter represents the first nonporphyrin iron complex capable of forming a stable dioxygen adduct at room temperature. 

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