Peroxo anions

Phase Transfer Catalysis (PTC) with tungsten anionic peroxo species for epoxidation of la... 

When the H2O2 treatment is made in basic media, a light yellow (or white) stable material is recovered, which was found to be an anionic peroxo derivative stabilized by the presence of the alkali metal ion. The adduct does not display oxidation properties, unless the pH of the suspension is brought to neutrality [55]. 

Likewise, within mechanism B, the /r-peroxo intermediate may be susceptible to reversible one-electron reduction to anionic [(dipor)Co202], which may become important only at potentials <0.5 V. There is some indication that the formally peroxo adducts, [(dipor)Co2 02 )], formed by addition of O2 to fully reduced (dipor)Co2, may undergo reversible reduction. Protonation of the anionic species may be followed by its hydrolysis, releasing H2O2. 

The aqueous solution chemistry of Tc(VII) is dominated by the stability of the TeO anion [4], Nitrido complexes are few and are limited to peroxides and one dimeric nitrido-hydrazido example. The peroxo complexes based on the [TcVIIN(02 )2] core are analogous to the well-known isoelectronic [MoviO(02)2] complexes [117] and are the only examples of nitridoperoxo complexes and rare examples of peroxo complexes of a metal in the +7 oxidation state. 

Single crystals of peroxomonosulfuric acid, H2S05 (also known as Caro s acid) have been prepared by the reaction of fuming sulfuric acid and H202. In the crystal structure, the molecules are connected via hydrogen bonds.49 The distance within the peroxo group of the anion is 1.46 A. 

The electropositive metal center polarizes the peroxo group so that is much more electrophilic than free peroxide anion. Evidence has been accumulated, and it will be summarized later, that such polarization happens to the extent that nucleophilic reagents can attack a peroxo oxygen when it is coordinated to a d° metal. In other words, this situation... 

Salts with oxometallate anions function as oxidants, those with oxygen present as peroxo groups being naturally the more powerful, and separately grouped under See also peroxoacid salts... 

METAL NITROPHENOXIDES, METAL OXALATES METAL PYRUVATE NITROPHENYLHYDRAZONES metal OXOHALOGENATES (anion an oxo derivative of a halogen) metal oxometallates (anion an oxo derivative of a metal) metal oxonon-METALLATES (anion an oxo derivative of a non-metal) peroxoacid SALTS (anion a peroxo derivative of a metal or non-metal) There is a separate entry for... 

Another anion pair held together by a short hydrogen bond is [H V0(02)2(bipy) 2] [4] in which two peroxo complex anions are linked, with Rq-. q- 245.6 pm (Szentivanyi and Stomberg, 1984). An example of an uncharged system with a very short hydrogen bond is that of 2-(N,N-diethylamino-JV-oxymethyl)-4,6-dichlorophenol [5], with o = 240pm (Koll et al 1986). 

Some of these ideas incorporating a pterin radical are outlined in Fig. 9. Here the pterin serves as an electron donor to the oxy intermediate to give the peroxy di-anion. The substrate, L-Arg, itself serves as the proton donor to the peroxo intermediate as proposed by Crane et al. (80), which is required for heterolytic cleavage of the peroxide 0—0 bond. The proton delivery machinery outlined in Fig. 9 could also help to explain why peroxide itself cannot support the conversion of L-Arg to N°-hydroxy-L-Arg (126). The reaction may require a potent base like... 

Fig. 14. Manifold of reactive species produced from the reaction of a heme group with oxygen and two reducing equivalents. The rate of conversion of A to B limits the lifetime (and therefore reactivity) of the Fe peroxo anion. The rate of formation of the ferryl species C via the Fe -OOH complex B competes with the intramolecular hydroxylation reaction to give hydroxyheme. Reactions of the Fe -hydroperoxy complex B with exogenous electrophilic substrates must compete with conversion of the intermediate to both C and meso-hydroxyheme. The Fe -OOH complex B can also be formed directly with H2O,.

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