22541-77-1Relevant academic research and scientific papers
Reactions of vanadium(IV) and (V) with s2 metal-ion reducing centers
Yang, Zhiyong,Gould, Edwin S.
, p. 3963 - 3967 (2003)
The s2 centers, Sn(II), Ge(II), and In(I) reduce VO2+ rapidly and quantitatively to VO2+, and In(I) converts VO2+ (much more slowly) to V3+. Sn(II) and Ge(II) react measurably with VO2+ only in chloride media in the presence of added Cu(II). Arguments are presented that the V(v) reductions are initiated by a two-unit reduction to V(III) (via a hydroxo bridge), followed by a rapid comproportionation (VIII + VV → 2 VIV). The Cu(II)-catalyzed V(IV)-Sn(II) and V(IV)-Ge(II) reactions at high [Cl-] involve preliminary conversion of the catalyst to Cu(I), which then reduces V(IV), and kinetic profiles of the Ge(II) system point to participation of chloride-bound Ge(III) as well.
Bimolecular homolytic reactions of alkylcobalt complexes
Lee, Shaoyung,Ku, Tsung Yao
, p. 2901 - 2905 (2008/10/09)
The reactions of RCoL1(H2O)2+ (R = CH3, C2H5 and n-C3H7; L1 = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) and CH3CoLsu
Molybdenum and copper catalysis of reductions by titanium(II) and titanium(III)
Yang, Zhiyong,Gould, Edwin S.
, p. 396 - 398 (2007/10/03)
Reductions of vanadium(iv), benzoquinone, and tri-iodide, both by titanium(iii) and by titanium(ii), are catalyzed by molybdenum(vi). The VO 2+-Ti(ii) reaction is catalyzed by copper(ii) as well. Reactions of Ti(ii) with the oxidant in excess y
Reactions of tris(oxalato)cobaltate(in) with two-electron reductants
Yang, Zhiyong,Gould, Edwin S.
, p. 3601 - 3603 (2007/10/03)
The tris(oxalato)cobaltate(in) complex [Co(C2O4) 3]3-, EoCoIII/II = +0.57 V) is readily reduced by the 2e- reagents, Sn(II) and Ge(ii), in contrast to (NH3)5CoCl2+ and (NH3) 5CoBr2+, which are unreactive toward these donors. Rates for the oxalato oxidant are only 10-3-10-2 as great as those for vitamin B12a (aquacob(III)alamin, Eo +0.35 V at pH 1), in accord with the suggestion that reductions of corrin-bound cobalt(III) by Sn(II) and Ge(II) occur predominantly through an additional path involving Co(I). Reductions of the oxalato complex by 2e- donors are taken to proceed by initial formation of odd-electron intermediates (e.g., Sn III and GeIII) which react rapidly with CoIII. Such a two-step sequence is in keeping with the observed behavior of the rare reductant, TiII, which is found to be oxidized by [Co(C 2O4)3]3- more slowly than (independently prepared) Ti(III) under comparable conditions.
2′-Hydroxyacetophenonebenzoylhydrazone as an analytical reagent for the spectrophotometric determination of vanadium(III)
Agnihotri,Dass,Mehta
, p. 165 - 167 (2007/10/03)
2′-Hydroxyacetophenonebenzoylhydrazone (HABH) forms a light red 1:2 (V : HABH) complex with VIII species at 50-60° in 0.12-0.20 M CH3COOH medium which is extracted into benzene and has λmax at 465 nm. The molar absorptivity, Sandell's sensitivity and standard deviation arc 1.05 × 104 dm3 mol-1 cm-1, 0.0049 μg V cm-2 and ±0.0006 respectively, at 465 nm. Beer's law is obeyed over the concentration range 0-1.5 μg V ml-1. Large number of elements do not interfere. The method can be used to determine vanadium in a wide variety of synthetic and technical samples including alloyed steel and reverberatory flue dust.
Kinetics of oxidation of iodide by vanadium (V)
Nadh, R. Venkata,Sundar, B. Syama,Radhakrishnamurti, P. S.
, p. 75 - 78 (2007/10/03)
Kinetics of oxidation of iodide ion by VV under uncatalysed and RuIII catalysed conditions in aqueous perchloric acid medium have been studied. The reaction is first order in [VV] and first order in [I-]. With [H+], the reaction shows a complex behavior of 1.5 order till [H+] is 0.5 M and second order beyond that concentration. In the case of RuIII catalyzed oxidation, the reaction exhibits a dual character of first order and zero order in [VV]. The first order component shows 1.5 order in [I-] first order in III> and 1.5 order in [H+]. The zero order component shows first order in [I-], first order in [RuIII] and independent of [H+]. No catalysis has been observed with OsVIII. Suitable rate laws have been postulated based on the observations.
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.
Copper colloids stabilized by water-soluble polymers. Part II. Their application as catalysts for dihydrogen evolution
Savinova,Savinov,Parmon
, p. 231 - 248 (2008/10/08)
The kinetics of catalytic dihydrogen evolution from acidic aqueous solutions of strong one-electron reductants Vaq2+ and the cation radical of methylviologen (MV+.) in the presence of polymer-stabilized copper colloids was
Cobalt-catalyzed evolution of molecular hydrogen
Connolly, Philip,Espenson, James H.
, p. 2684 - 2688 (2008/10/08)
Solutions of chromium(II), europium(II), or vanadium(II) chloride in hydrochloric acid evolve molecular hydrogen rapidly in the presence of trace concentrations of the cobalt(II) macrocycle Co(dmgBF2)2. The stoichiometry for Cr(II) corresponds to the net reaction Cr2+ + Cl- + H+ = CrCl2+ + 1/2H2. The kinetics are described quite adequately by the Michaelis-Menten scheme. Kinetic studies of the reaction were made during the pre-steady-state phase, during which an intensely absorbing intermediate forms, and also at longer times during the steady-state phase when the pseudo-steady-state concentration of the intermediate slowly declined as the substrate was consumed. Arguments are given in support of the intermediate being [(H2O)5Cr-Cl-Co(dmgFB2)2] +. Its dissociation leads, in acidic solution, to the hydridocobalt complex HCo(dmgBF2)2, which is responsible for H2 formation. Bromide ions, but not perchlorate, also give catalytic H2 production, whereas iodide forms a ternary complex that does not decompose.
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.
