Reaction of hydrogen peroxide with the oxochromium(IV) ion by hydride transfer

Oxidation of hydrogen peroxide by pentaaquaoxochromium(IV), (H[sub 2]O)[sub 5]CrO[sup 2+], in aqueous acidic solutions (0.10-1.0 M HClO[sub 4]) yields the superoxochromium(III) ion (H[sub 2]O)[sub 5]CrOO[sup 2+]. The same product is obtained in both the presence and the absence of oxygen. In 0.10 M...

Full description

Saved in:
Bibliographic Details
Published in:Inorganic chemistry 1993-07, Vol.32 (14), p.3162-3165
Main Authors: Al-Ajlouni, Ahmad M, Espenson, James H, Bakac, Andreja
Format: Article
Language:English
Subjects:
400201 - Chemical & Physicochemical Properties
400202 - Isotope Effects, Isotope Exchange, & Isotope Separation
ABSORPTION SPECTRA
ACTIVATION ENERGY
ARRHENIUS EQUATION
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
Chemistry
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
ENERGY
EQUATIONS
Exact sciences and technology
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
Inorganic chemistry and origins of life
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
IONS
ISOTOPE EFFECTS
KINETICS
Kinetics and mechanism of reactions
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PEROXIDES
PHYSICAL PROPERTIES
REACTION KINETICS
SPECTRA
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Oxidation of hydrogen peroxide by pentaaquaoxochromium(IV), (H[sub 2]O)[sub 5]CrO[sup 2+], in aqueous acidic solutions (0.10-1.0 M HClO[sub 4]) yields the superoxochromium(III) ion (H[sub 2]O)[sub 5]CrOO[sup 2+]. The same product is obtained in both the presence and the absence of oxygen. In 0.10 M HClO[sub 4] the second-order rate constant at 25[degrees]C is 190[+-]10 L mol[sup [minus]1] s[sup [minus]1] in O[sub 2]-saturated solutions and 172[+-]8 L mol[sup [minus]1] s[sup [minus]1] in Ar-saturated solutions, independent of acidity and ionic strength in the range 0.10-1.0 M (HClO[sub 4]/LiClO[sub 4]). In D[sub 2]O a solvent the rate constant is k[sub D] = 53[+-]3 L mol[sup [minus]1] s[sup [minus]1], resulting in the kinetic isotope effect k[sub H]/k[sub D] = 3.6. Experiments in the temperature range 6.8-38.4[degrees]C yielded [delta]H = 25[+-]kJ mol[sup [minus]1] and [delta]S = [minus]116[+-]8 J mol[sup [minus]1] K[sup [minus]1]. A hydride-transfer mechanism is suggested for the oxidation of H[sub 2]O[sub 2] by CrO[sup 2+]. It involves the coordination of H[sub 2]O[sub 2] to Cr(IV) prior to the hydride abstraction step. The reaction of HCrO[sub 4][sup [minus]] with H[sub 2]O[sub 2] under the same conditions also yields (H[sub 2]O)[sub 5]CrOO[sup 2+], which was identified by its characteristic UV spectrum. Possible mechanisms for these reactions are discussed.
ISSN:0020-1669
1520-510X
DOI:10.1021/ic00066a030