Oxyhalogen Anions

The rate law for I04(H4l06) oxidation of chromium(III) to chromium(VI) has a second-order dependence on [Cr(III)] concentration and the reaction involves formation of a periodate-bridged chromium dimer [Cr(0H)I04HCr0H] which decays at a rate in excess of 1.29 x 10 s at 25°C and 0.25 M ionic strength with two simultaneous one-electron transfers from the metal centers to the bridge. 

Oxidation of cobalt(II) aminocarboxylates [CoHEDTA] and [CoEDDA] by IO4 is first order in metal complex but two pathways with first- and second-order dependencies on [IO4] concentration are detected, indicating intermediate mono- and bis-complex formation. Both complexes are redox active and second- and third-order rate constants are 0.16M s and 2.59M s for [CoHEDTA] and 0.120 M s and 1.53 M s for [CoEDDA] at pH 5, 25°C, and 0.5 M ionic strength. The third-order rates are pH dependent. 

Three different reactions are detected in the IO4 oxidation qf 2,3-dihydroxypropyl cobalamin. Periodate attacks the diol function of the base on and base off complexes with acid-catalyzed rate constants of 2.4 X 10 M s and 2.0 x 10 A/ s to give B 12a in a pathway which 

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It is convenient to classify here the decompositions of metal salts of the various oxyhalogen acids on the basis of the oxygen content of the anion, with subsections devoted to the metals of a particular sub-group of the Periodic Table. Again, consideration of the ammonium salts is deferred to Sect. 4. As noted elsewhere in this review, some reports are not explicit as to whether or not melting accompanies reaction thermal analysis studies can be valuable [843]. 

The high values of E generally characteristic of the decomposition reactions of metal oxyhalides are widely interpreted as evidence that the initial step in anion breakdown is the rupture of the X—O bond and that the energy barrier to this reaction is not very sensitive to the properties of the cation present. Information of use in the formulation of reaction mechanisms has been obtained from radiolytic studies of oxyhalogen salts [887-889],... 

Yoshida and coworkers47 reported that they readily oxidized bromide and chloride anions into positive halogens with p-nitrobenzenesulfonyl peroxide (equation 26). They found that oxyhalogenated products were formed from the reaction of these positive halogens with olefins, and proposed epihalonium ion intermediates which, in turn, were trapped by oxygen nucleophiles inter- or intramolecularly to afford the oxyhalogenated products (equation 27). 

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