The Kinetics of the Electron Exchange between the 12-Tungstocobaltate(II) and the 12-Tungstocobaltate(III) Anions in Aqueous Solution

Kinetics and mechanism of oxidation of antimony(III) by keggin‐type 12‐tungstocobaltate(III) in aqueous hydrochloric acid medium

“…Sb(III) solution was prepared by dissolving SbCl 3 (British Drug House (BDH)) in 3.5 mol dm −3 HCl and standardized against bromate in 3.5 mol dm −3 HCl. The cobalt complexes [Co III W 12 O 40 ] 5− and [Co II W 12 O 40 ] 6− were prepared by the reported method 30, 31 and standardized spectrophotometrically 32 (at 624 nm, ε 624 = 180 ± 2 dm 3 mol −1 cm −1 for [Co II W 12 O 40 ] 6− and at 388 nm, ε 388 = 1150 ± 2 dm 3 mol −1 cm −1 for [Co III W 12 O 40 ] 5− , respectively) using an Elico SL 159 UV–vis spectrophotometer. The solution of Sb(V) was prepared by dissolving K[Sb(OH) 6 ] in 2 mol dm −3 HCl and its concentration was ascertained by iodometric titration with standard thiosulphate.…”

Oxidative behavior and relative reactivities of some unsaturated compounds towards hexachloroiridate(IV) in perchloric acid medium

“…The difference in absorbance ( A) of two solutions, both containing Ir(IV) and perchloric acid in DMF-water mixture, and one of them furthermore styrene, was measured. K e was calculated using the relation (3) [23].…”

Ionic-strength dependence of electron-transfer reactions of Keggin heteropolytungstates: Mechanistic probes of O2 activation in water

“…In 1983, Eberson [5] used Co III W 12 O 40 5− to investigate the mechanism of electron-transfer oxidation of benzyllic C-H bonds. The data analysis included use of the Marcus cross relation [6], the application of which took advantage of kinetic parameters (reorganization energies, λ) published by Rasmussen and Brubaker [7] in 1964. These λ values were obtained by measuring the rates the electron self-exchange between Co III W 12 7− (an electron donor), as well as other Keggin anions, simpler isopolyanions, and Wells-Dawson anions, have been used as mechanistic probes to investigate a wide range of electron transfer reactions, involving both inorganic and organic substrates [3].…”