Kinetics and mechanism of the oxidation of a ferrous complex with an α,α′-diimine chelate ligand by ceric sulfate in aqueous acidic medium by UV-vis absorption spectroscopy

Abstract

Kinetics of the oxidation of tris(2,2ƍ-bipyridine)iron(II) sulfate by ceric sulfate was spectrophotometrically studied in an aqueous sulfuric acid medium. Different methods, including isolation, integration and half-life, were employed to determine the reaction order. The redox reaction was found to be first-order with respect to the reductant, tris(2,2ƍ-bipyridine)iron(II) sulfate, and the oxidant, ceric sulfate. Complex kinetics was observed with an increase in the initial concentration of the oxidant. The influence of the dielectric constant, [H + ] and [SO 4 2-] on the rate was also investigated. The increase in the dielectric constant and H + ion concentration of the medium retard the rate, while an increase in the SO 4 2-ion concentration first accelerates the rate, and then retards the reaction. The effect of each factor, i.e., the dielectric constant, H + ions and SO 4 2-ions, suggests that Ce(SO 4 ) 3 2-is

Boron Cluster Anions [BnHn]2– (n = 10, 12) in Reactions of Iron(II) and Iron(III) Complexation with 2, 2′‐Bipyridyl and 1, 10‐Phenanthroline

“…Recently, 1, 10‐phenanthroline mono N‐oxide was shown to be an autocatalyst in the decomposition of [Fephen 3 ] 3+ , and the proposed mechanism involves Fe IV complex [Fephen 3 ] 4+ as a minor intermediate 23. Therefore, ferric [FeL 3 ] 3+ complexes can be obtained only by oxidation of ferrous [FeL 3 ] 2+ complexes using strong oxidized agents (for example, Ce 4+ cations24). Stabilization of the obtained forms needs presence of an oxidizer in the reaction mixture.…”

Kinetics of the oxidation of iodide by dicyanobis(phenanthroline)iron(III) in a binary solvent system

“…The order of reaction with respect to the oxidant and the reductant was determined by implementing a series of equations (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The reaction was probed under the pseudo-first order-condition via keeping reductant in excess over oxidant.…”

“…Consequently, the electrontransfer mechanism depends upon these parameters. 11 The oxidation of the iodide ion in acetonitrile was first order with respect to dicyanobis(bipyridine)iron(III). However, the observed first-order rate constant increased nonlinearly with increasing concentration of the iodide ion.…”

“…This is well known that the electrolyte and its nature, solvent system, and its nature and acidity of the medium are the parameters that can enhance or reduce the reduction potential of the species. Consequently, the electron‐transfer mechanism depends upon these parameters 11 . The oxidation of the iodide ion in acetonitrile was first order with respect to dicyanobis(bipyridine)iron(III).…”

Catalytic Effect of 1,4-Dioxane on the Kinetics of the Oxidation of Iodide by Dicyanobis(bipyridine)iron(III) in Water

“…In DSSC, polypyridyl liganded Co(III)/(II) redox couples have been widely used, with a system efficiency of 14% [35,51]. Consequently, the transition metal complexes of Fe(III)/(II) with polypyridyl ligands may have the potential to increase the performance of the DSSC if used as a sensitizer to oxidize iodide [13,36,[52][53][54][55][56][57][58][59][60][61][62][63][64][65].…”