Hydride osmium kinetics

Cp M(H)2(dppe)] + for M = Os. For all three metal hydrides the Vmh band of the starting hydride disappear upon protonation but only in the case of osmium new Vmh bands appear in the IR spectra (Table 10). When these kinetic protonation products transform into thermodynamically more stable truTO-[Cp M(H)2(dppe)] the corresponding Vmh bands appear in the IR spectra for all three metals (Table 10). Thus, such spectral changes can be used to monitor the protonation reaction. 

The oxidation of DL-methionine by sodium iV-chlorotoluene-p-sulfonamide (CAT) in alkaline medium catalysed by OSO4 shows a first-order dependence each on CAT and methionine, an inverse fl actional-order dependence on HO , and a fractional-order dependance on 0s04. " The oxidation of mono-, di-, and tri-ethanolamine (MEA, DEA, and TEA, respectively) by CAT " and sodium A-bromotoluenesulfonamide (bromamine-T, BAT) " in alkaline buffer is first order in oxidant and fractional order each in substrate and HO. The oxidation rate increased in the order di- > tri- > mono- and suitable mechanisms consistent with the kinetic data have been proposed. Osmium(Vni)-catalysed oxidation of propane-1,3-diol by CAT in alkaline medium proceeds via hydride-ion abstraction fi om the a-carbon of the diol. " ... 

Oxidation of aliphatic aldehydes by benzyltrimethylammonium chlorobromate to the corresponding carboxylic acid proceeds via the transfer of a hydride ion from the aldehyde hydrate to the oxidant. The oxidation of aUyl alcohol with potassium bromate in the presence of osmium(Vin) catalyst in aqueous acidic medium is first order in bromate, Os(Vni) and substrate, but inverse fractional order in H+ the stoichiometry of the reaction is 2 3 (oxidantsubstrate). The active species of oxidant and catalyst in the reaction were understood to be BrOs and H2OSO5, respectively, which form a complex. Autocatalysis by Br, one of the products, was observed, and attributed to complex formation between Br and osmium(VIII). First-order kinetics each in BrOs, Ru(VI), and substrate were observed for the ruthenium(VI)-catalyzed oxidation of cyclopentanol by alkaline KBrOs containing Hg(OAc)2. A zero-order dependence on HO concentration was observed and a suitable mechanism was postulated. The oxidation reaction of aniUne blue (AB+) with bromate at low pH exhibits interesting non-linear phenomena. The depletion of AB+ in the presence of excess of bromate and acid occurs at a distinctly slow rate, followed by a very rapid reaction. A 12-step reaction mechanism, consistent with the reaction dynamics, has been proposed. The novel cyclohexane-l,4-dione-bromate-acid system has been shown to exhibit a rapid oscillatory redox reaction superimposed on a slower... 

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