Transition metal complexes peroxo

Li-peroxo transition metal complexes, 1060 Conductivity, oxidation stability measurement, 664... 

McLain, J. L. Lee, J. Groves, J. T. Biomimetic oxygenations related to cytochrome P450 metal- and metal-peroxo intermediates, Biomimetic Oxidations Catalyzed by Transition Metal Complexes , Ed. Meunier, B. Imperial College Press London, 2000, pp. 91-169. 

In Fig. 1 some of the most common metal-dioxygen binding modes found for mononuclear and dinuclear transition metal complexes are diagrammed. Note that the terms superoxo and peroxo ultimately... 

These complexes can exist in a triangular peroxo form (7a) for early d° transition metals, or in a bridged (7b) or linear (7c) form for Group VIII metals. They can be obtained from the reaction of alkyl hydroperoxides with transition metal complexes (equations 9 and 10),42-46 from the insertion of 02 into a cobalt-carbon bond (equation ll),43 from the alkylation of a platinum-peroxo complex (equation 12),44 or from the reaction of a cobalt-superoxo complex with a substituted phenol (equation 13).45 Some well-characterized alkylperoxo complexes are shown (22-24). 

D. V. Deubel, J. Sundermeyer, G. Frenking, Olefin epoxidation with transition metal 2-peroxo complexes The control of reactivity, Eur. J. Inorg. Chem. (2001) 1819. 

The intermediate peroxospecies could not be detected even with H3PMoi2O40-t-BuOOH system. This indicates, like other transition metal complexes, heteropolymolybdate catalyses the thermal decomposition of t-BuOOH to give active free radicals like t-BuO Which in turn give only the side chain oxidized products or the open peroxo structure was formed as an intermediate like that of H5PV2M010O40 - H2O2 system which could not however be detected. 

Molecular oxygen adducts of transition metal complexes arc of interest and importance to catalytic processes and commercial oxidation processes, as well as being intermediates in oxidation reactions. Vaska " has reviewed the nature of dioxygen bound to transition metal complexes. All known iridium dioxygen complexes possess the peroxo structure (140). Experimental data reveal that the formation of covalent Ir—(O2) bonds on dioxygen addition to IrL, is accompanied by extensive redistribution of electrons, and the electron transfer is from the iridium to dioxygen. SCF-X -SW calculations on [Ir(02)(Ph3)4] and [Ir(Ph3)4] " indicate peroxo -metal bonding. ... 

Although the O2-binding transition metal complexes have been studied extensively, the nature of their bond formation has long been the subject of some controversy. Vaska (1976) showed that almost all currently known transition metal dioxygen complexes can be divided into two types according to the characteristics of the dioxygen ligand. They are the (type I) superoxo (02 ) and the (type 11) peroxo (02 ) complexes. These complexes are further classified... 

Dioxygen can be coordinated to transition metal complexes in low oxidations state. Depending on the ability of the metal to donate electrons, the adducts are formulated as superoxo or peroxo complexes, while in the case of bridging molecular oxygen mu-peroxo complexes can be formed. 

A fifth paper on this reaction seeks to clear up discrepancies between two sets of activation parameters reported for the k and k terms of this rate law. This paper also briefly discusses reactivities of 0x0- and hydroxo-bridged transition-metal complexes. Reactivities of these compounds can be compared with those for similar actinide species through kinetic results for decomposition of, for example, the [U020H]a + dimer, and the peroxo-bridged plutonium species [Pu—O2—PuOH] +. The rate of decomposition of this last complex is proportional to hydrogen ion concentration— there is just one acid-catalysed path here, in contrast to the parallel pH-dependent and pH-independent paths for the [Fe(OH)]a + dimer. 

An interesting example of dioxygen adducts of transition-metal complexes is the trans-planar [IrCl(CO)(PPh3)2] (Vaska s salt), which binds dioxygen reversibly to form a trigonal bipyramidal complex. The 0-0 distance of this compound (1.30 A) is close to that of the O2 ion (1.28 A) its v(02) (857 cm" ) is typical of peroxo adducts. 

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