Peroxide bridged complex

The postulated formation of the polynuclear peroxo intermediate has precedence in the literature of Fe(II)-porphyrin systems. In addition, the only structurally characterized non-heme iron(ni) peroxide complex, [Fe6(02)C>2(0Bz)i2] (5), has a structural motif similar to that in the key intermediate, namely, a p,p- n2, q2-peroxide spedes in which four ferric ions are coordinated to the peroxide dianion (I3 in Scheme 1). Because 5 has all ferric ions, this peroxide-bridged complex is stable. The species in Scheme 1, on the other hand, is mixed-valent Fe 2F 2/ and can therefore decompose by redox chemistry to form the stable (p-oxo)diiron(ni) product. 

Symmetrical diaLkyl peroxides are commonly named as such, eg, dimethyl peroxide. For unsymmetrical diaLkyl peroxides, the two radicals usually are hsted ia alphabetical order, eg, ethyl methyl peroxide. For organomineral peroxides or complex stmctures, ie, where R and R are difficult to name as radicals, the peroxide is named as an aLkyldioxy derivative, although alkylperoxy is stUl used by many authors. CycHc peroxides are normally named as heterocychc compounds, eg, 1,2-dioxane, or by substitutive oxa nomenclature, eg, 1,2-dioxacyclohexane however, when the two oxygens form a bridge between two carbon atoms of a ring, the terms epidioxy or epiperoxy are frequendy used. The resulting polycycHc stmcture has been called an endoperoxide, epiperoxide, or transaimular peroxide. 

The hexamine cobalt (II) complex is used as a coordinative catalyst, which can coordinate NO to form a nitrosyl ammine cobalt complex, and O2 to form a u -peroxo binuclear bridge complex with an oxidability equal to hydrogen peroxide, thus catalyze oxidation of NO by O2 in ammoniac aqueous solution. Experimental results under typical coal combusted flue gas treatment conditions on a laboratory packed absorber- regenerator setup show a NO removal of more than 85% can be maitained constant. 

Baldwin, M. J., P. K. Ross, J. E. Pate, Z. Tyeklar, K. D. Karlin, and E. I. Solomon. 1991. Spectroscopic and Theoretical Studies of an End-On Peroxide-Bridged Coupled Binuclear Cooper(II) Model Complex of Relevance to Active Sites in Hemocyanin and Tyrosinase. J. Am. Chem. Soc. 113, 8671. 

One of the most important peroxo complexes synthesized after 1983 is the rhenium species formed from methyltrioxorhenium (MTO) precursor. The synthesis of this complex is achieved in the way indicated in equation 2, by reacting hydrogen peroxide with MTO . The isolated peroxo complex 1 contains in the coordination sphere two /7 -peroxide bridges, a direct metal carbon bond and a molecule of water. The crystal structure of the peroxo rhenium derivative, however, was obtained by substitution of the water molecule with other ligands " more details on this aspect are enclosed in the structural characterization paragraph. 

Similar reactions have been reported (161) for cobaltocene with nitric oxide (NO). (See Scheme 13.) In this case, however, rather than producing the peroxide-bridged structure 63, the more stable ether-linked species 64 was produced. Complex 64 was crystallographically characterized, its reactions were studied, and a mechanism for its formation was proposed. 

This type of complex is derived from the mononuclear superoxo species via a further one-electron reduction of the dioxygen moiety. Cobalt is the only metal to form these complexes by reaction with dioxygen in the absence of a ligating porphyrin ring. Molybdenum and zirconium form peroxo-bridged complexes on reaction with hydrogen peroxide. In most cases the mononuclear dioxygen adducts of cobalt will react further to form the binuclear species unless specific steps are taken to prevent this. 

Complexes containing the Rh—02 moiety are now well known, but there have been a few false starts and misunderstandings along the way. The first claim for an 02 complex of rhodium was made by Wilkinson and co-workers,1141 who reported that [Rh(H)(CN)4(H20)]2 reacted with 02 to give the peroxide-bridged dimer [(H20)(CN)4Rh—02—Rh(CN)4(H20)]4. This was later disputed, and the reaction product identified as the protonated, peroxo monomer of Rh111, [Rh(02H)(CN)4(H20)]2. 1142 The solid is diamagnetic, and displays O—O stretches at 839 and 825 cm-1, characteristic of an unsymmetric monomer no such bands appear in the Co-peroxo dimer.1142. 

The discovery of artemisinin (Figure 8.16) by Chinese scienhsts in 1971 provided an excihng new natural product lead compound, and artemisinin is now used for the treatment of malaria in many countries. Its unusual endoper-oxide bridge is a key to its mechanism of achon, which involves complexation with haemin by coordination of the peroxide bridge with iron. This in turn interrupts the detoxi-hcahon process used by the parasite and generates free radical species which can attack proteins in the parasite. 

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