One‐step, two‐electron oxidation of cis‐diaquabis(1,10‐phenanthroline)chromium(III) to cis‐dioxobis(1,10‐phenanthroline)chromium(V) by periodate in aqueous acidic solutions

Abstract

The pseudo-first-order rate constant, k obs , increased with increasing pH, indicating that the hydroxo form of the chromium(III) complex is the reactive species. An inner-sphere mechanism has been proposed for the oxidation process. The thermodynamic activation parameters of the processes involved are also reported. C

Kinetics and Mechanistic Studies of Oxidation of a Ternary Nitrilotri-Acetatocobalt(II) Complexes Involving DL-valine and DL-aspartic Acid as a Secondary Ligands by Periodate

“…The lability of cobalt(II) reactants and the inertness of cobalt(III) products could be utilized as a diagnostic tool for ascertaining inner-sphere electron transfer [10,[13][14][15]. Oxidation of some cobalt(II) complexes by periodate, where an initial cobalt (III) product was observed, was interpreted in terms of this mechanism.…”

“…In view of the above considerations, kinetics of oxidation of [Co II (NTA)L(H 2 O) x ] -n by periodate proceeds by one firstorder pathway in each reactant. The mechanism could be described by the following equations (10)(11)(12)(13)(14). (13) From the above mechanism, the rate of the reaction can be described by Equation 14,…”

“…Using periodate as an oxidant for inorganic substrates and some transition metals are reported to proceed via an innersphere mechanism [10][11][12][13][14][15]. Periodate readily found to oxidize either labile or inert complexes possessing at least one bridging ligand.…”

“…Periodate readily found to oxidize either labile or inert complexes possessing at least one bridging ligand. Initial cobalt(III) products that were transformed to the final cobalt(III) products slowly were identified spectrophotometrically [13][14][15].…”

Inner-sphere oxidation of a ternary dipicolinatochromium(III) complex involving a malonic acid co-ligand

“…11, where the value of K 4 (3.17 3 10 -4 ) was determined in this work by a potentiometric method at 30°C and I = 0.20 mol dm -3 . 2 ]to chromium(VI) can proceed through one-or two-electron transfer, producing a chromium(IV) or chromium(V) intermediate, respectively, in the rate-determining step of these two possibilities; the latter pathway is more likely [19,23]. Therefore, Eqs.…”