Catalytic O2 evolution from water induced by adsorption of [(OH2)(Terpy)Mn(μ-O)2Mn(Terpy)(OH2)] 3+ complex onto clay compounds

Yagi, Masayuki,Narita, Komei

, p. 8084 - 8085 (2004)

Water oxidation to evolve O2 in photosynthesis is catalyzed by an enzyme whose active site contains a μ-oxo-bridged manganese core. Catalytic O2 evolution has been difficult to establish by manganese-oxo complexes in homogeneous aqueous solutions. The reaction of [(OH2)(terpy)MnIII(μ-O)2MnIV(terpy)(OH2)]3+ (terpy = 2,2′:6′,2″-terpyridine) (1) with a CeIV oxidant leads to the decomposition of 1 to the permanganate ion without O2 evolution in an aqueous solution but catalytically produces O2 from water when 1 is adsorbed on clay compounds. 18O-labeling experiments showed that the oxygen atoms in O2 originate exclusively from water. Catalysis of O2 evolution requires cooperation of 2 equiv of 1 adsorbed on clay compounds. Copyright

The oxidation of chlorine ions under the joint action of ozone and permanganate ions

Levanov,Kuskov,Antipenko,Lunin

, p. 557 - 561 (2006)

The oxidation of chlorine ions in the system O3 + MnO 4 - + H+ + Cl- with the formation of Cl2 in the gas phase was studied. The phenomenon of transfer catalysis of the reaction between O3 and Cl- by the MnO 4 - ion was observed (the products of the reduction of MnO 4 - by the chlorine ion are oxidized by ozone to recover MnO 4 - ). The rate of the formation of Cl2 in the O3 + MnO 4 - + H+ + Cl - system was higher than the sum of the corresponding rates in the oxidation of Cl- by O3 and MnO 4 - separately. A scheme explaining the trends observed experimentally for the formation of Cl2 and changes in MnO 4 - concentration was suggested. The formation of MnO 4 - in the oxidation of Mn3+ with ozone in acid media was studied. Pleiades Publishing, Inc., 2006.

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Melendez,Brenet

, p. 61 - 77 (1971)

Kinetic data of a manganese electrode immersed in phosphoric acid solutions at different pH have been established with the aid of polarisation curves obtained by the potentiodynamic method. The passivation phenomena of manganese by the formation of phosphates and the adsorption of oxygen have been obtained on the basis of the data and the theoretical of pH/potential diagrams. It has been established that the rate of spontaneous corrosion is controlled by the diffusion of the Mn(II) phosphate in the solution.

Kinetics and Mechanism of the Permanganate Ion Oxidation of Sulfite in Alkaline Solutions. The Nature of Short-Lived Intermediates

Simandi, Laszlo I.,Jaky, Miklos,Savage, C. R.,Schelly, Z. A.

, p. 4220 - 4224 (1985)

The oxidation of sulfite by permanganate ion has been studied by the stopped-flow technique combined with rapid scan spectrophotometry.The overall reaction involves manganate(VI) as an intermediate, whose fate depends on the pH.The formation and disappearance of manganate(VI) represent two distinct phases: (1) reduction of permanganate to manganate(VI) via outersphere electron transfer; (2) slower disproportionation of manganate(VI) to permanganate and a soluble manganese(VI) product.The direct oxidation of sulfite by manganate(VI) is too slow to compete with the permanganate route.Manganate(V) has been detected for the first time by rapid scan spectrophotometry as an intermediate of manganate(VI) disproportionation.The first phase obeys overall second-order kinetics, the rate constant being pH-independent between 13 and 9.5.Disproportionation is second order in manganate, and the observed rate constant increases with decreasing pH.

Willard, H. H.,Greathouse, L. H.

, p. 2366 - 2366 (1917)

Estimation of One-Electron Oxidation Potentials of Some Donors Based on Data of Rate Constants for Their Interactions with Chlorine Dioxide

Kozlov, Yu. N.

, p. 218 - 220 (2007/10/02)

Reduction of ClO2. by various one- and two-electron donors is studied.The electron transfer rate constants (k) for the donors were measured directly, and their one-electron redox potential (φ) were either obtained by direct thermodynamic measurements or reliably established by various estimations and calculations with convergent results.An approximate linear dependence was found: log k = -12φ + 14.3, where k is in mol-1 s-1 and φ is in V.This dependence and the results of kinetic measurements are used to obtain the following one-electron redox potentials: φ(Sn3+/Sn2+) = 0.97 V, φ(PhO./PhO-) = 0.58 - 0.65 V, φ(SO3.-/SO32-) = 0.66 V, and φ(HCOO./HCOO-) = 1.45 V.