20644-97-7Relevant articles and documents
Photochemical Reactions of the Oxoperoxovanadium(V) Complex in an Acidic Aqueous Solution
Shinohara, Nobuyoshi,Nakamura, Yayoi
, p. 734 - 737 (1989)
The photochemical decomposition of oxoperoxovanadium(V), VO(O2)+, was studied in perchloric acid media.It was found that the irradiation of VO(O2)+ solutions with 313, 365, and 436 nm exciting light resulted in the photoreduction of
Kinetics and mechanisms of the redox reactions of the hydroperoxochromium(III) ion
Wang, Wei-Dong,Bakac, Andreja,Espenson, James H.
, p. 5034 - 5039 (2008/10/08)
The reactions of the hydroperoxochromium(III) ion, (H2O)5CrO2H2+ (CrO2H2+), with Fe2+, VO2+, V2+, Cu+, Ti3+, Co([14]aneN4)2+, Co(Me6[14]aneN4)2+, Co(tim)2+, and [Ru(NH3)6]2+ have been studied in acidic aqueous solution. The reactions are accompanied by large negative entropies of activation, -110 J mol-1 K-1 for Fe2+ and -85 J mol-1 K-1 for Ti3+. All the reactions studied follow an isokinetic relationship in that ΔH? is a linear function of ΔS?. The same is true for the analogous reactions of H2O2. It is proposed that the reactions of CrO2H2+ take place by an inner-sphere, Fenton-type process yielding pentaaquaoxochromium(IV), (H2O)5CrO2+ (CrO2+), as an intermediate. The reactivity of CrO2H2+ as an oxygen transfer reagent is about 20 times greater than that of H2O2. For example, the reactions with (en)2CoSCH2CH2NH22+ to yield (en)2CoS(O)CH2CH2NH22+ have rate constants 20.5 ± 0.4 M-1 s-1 (CrO2H2+) and 1.36 M-1 s-1 (H2O2), both in 0.1 M HClO4 at 25°C. The chromyl ion, CrO2+, oxidizes CrO2H2+ to CrO22+ with a rate constant of (1.34 ± 0.06) × 103 M-1 s-1 in 0.10 M HClO4 in H2O and 266 ± 10 M-1s-1 in D2O.
Kinetics and mechanism of oxidation of vanadium (2+) by molecular oxygen and hydrogen peroxide
Rush, James D.,Bielski, Benon H. J.
, p. 4282 - 4285 (2008/10/08)
The reaction between hexaaquovanadium(II), V(H2O)62+, and molecular oxygen has been studied by the stopped-flow method in 0.12 M perchloric acid and in solutions containing 0.1 M sulfate ion. The kinetics and stoichiometry of the reactions are consistent with a general oxidation mechanism for divalent transition-metal ions proposed by Ochiai.2 The following kinetic parameters have been determined: k2(2V2+ + H2O2) = 17.2 ± 2.0 M-1 s-1; k3(V2+ + O2) = (2.0 ± 0.2) × 103 M-1 s-1; k4((V·O2)2+ estimated dissociation) = 100 ± 50 s-1; k5((V·O2)2+ + V2+) = (3.7 ± 0.5) × 103 M-1 s-1; k-5((V·O2·V)4+ dissociation) = 20 ± 5 s-1; k6((V·O2·V)4+ decomposition) = 35 ± 5 s-1. At low V2+ concentration (2+, are produced/mol of oxygen consumed. At higher [V2+], a limiting ratio of Δ[VO2+]/Δ[O2] = 2 is approached and a limiting rate constant for VO2+ formation of 40 ± 5 s-1 is reached in both sulfate and perchlorate solutions.
Kinetics and Mechanism of Oxalic Acid Catalysed Oxidation of Nitrous Acid by Vanadium(V)
Dikshitulu, L. S. A.,Chandrasekharam, G.,Rao, V. Hanumantha,Vani, P.
, p. 150 - 153 (2007/10/02)
The kinetics and mechanism of the oxalic acid catalysed oxidation of nitrous acid by vanadium(V) have been studied in 1 M perchloric acid medium.The reaction is first order each in vanadium(V) and nitrite and fractional order in oxalic acid.Nitrate ion retards the rate of the reaction.At low +>(0.5-1.2 M) the rate of the reaction is independent of +> but at higher concentrations, the rate decreases.Kinetic as well as spectrophotometric evidence for the formation of a 1:1 complex between vanadium(V) and oxalic acid has been obtained and a mechanism involving this complex has been proposed.
Oxidation of peroxovanadium (V), VO3+, by HSO5- and Co3+ in acidic aqueous solution. Role of the VO32+. Radical cation
Thompson, Richard C.
, p. 859 - 863 (2008/10/08)
The oxidation of VO3+ by HSO5- is catalyzed by low concentrations of VO2+ in acidic solution. The rate law is -d[HSO5-]/dt = -d[VO3+]/dt = k1[HSO5-] [VO2+]0. The value of the rate parameter fc, is the same as that found previously for the HSO5--VO2+ reaction. A mechanism is proposed in which SO4-·, formed in the rate determining step, oxidizes VO3+ to the VO32+· radical cation. The VO32+· cleanly undergoes an internal redox reaction to produce VO2+ and O2. With relatively high concentrations of VO2+, VO3+ and VO2+ competitively reduce SO4-·; the ratio of the rate constants was estimated. Aqueous Co3+ oxidizes VO3+ to VO32+· according to the rate expression -d[VO3+]/dt = k5[VO3+][Co3+]. The VO32+· intermediate again undergoes an internal redox reaction; at later stages in the overall reaction, the resulting VO2+ competes with VO3+ for Co3+. The ratio of the rate constants in this competition was determined. Thus, the primary mode of oxidation of VO3+ is a one-electron process, at least with Co3+ and even the potentially multiequivalent oxidant HSO5-. It is concluded that the use of peroxo complexes is a promising means of distinguishing between one- and two-electron oxidations of the peroxide moiety.
The rates and mechanism of hydrolysis reactions of some metal acetylacetonates
Pearson, Ralph G.,Moore, John W.
, p. 1528 - 1532 (2008/10/08)
Rates of hydrolysis of acetylacetone complexes of oxovanadium(IV) and beryllium(II) have been measured using a stopped-flow technique. In aqueous solution at 25° VO(acac)2 decomposes in two steps with the second ring being removed 150 times slower than the first. Both rings were removed from Be(acac)2 at the same rate. The hydrogen ion dependence of the rates indicates that the special chelate mechanism, in which H+ traps a half-bonded intermediate, is a general one for hydrolysis of acetylacetonates. The behavior of hydrolysis rates upon addition of nucleophilic reagents is consistent with the interpretation that direct nucleophilic attack on the metal ion does not occur. The vanadyl complex, however, can add a sixth group which influences the rate of dissociation.
