The kinetics of the oxidation of iodide ions by octacyanomolybdate(V) ions in aqueous solution

Ford-Smith, M. H.; Rawsthorne, James

doi:10.1039/j19690000160

Cited by 21 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…More recently, Ferranti (39) studied the Mo(CN),~-/Ireaction, but his results are not too different from those of Ford-Smith and Rawsthorne. Inner-sphere coordination of tris-(1, 10-phenanthroline)iron(III) to halide ions is also unlikely, since a simple secondorder rate law, as observed by Ford-Smith and Rawsthorne (38), is obtained here, and catalysis by chloride and bromide ions rather than inhibition is observed. The added anions could associate with atomic iodine while it is in the process of being formed and since the added anion [X-] stabilises I, it lowers the energy barrier for the reaction.…”

Section: Discussionsupporting

confidence: 58%

Kinetics and mechanism of oxidation of tris-(1,10-phenanthroline)iron(II) by chlorine and bromine and of the reduction of tris-(1,10-phenanthroline)iron(III) by iodide ions

Ige¹,

Ojo²,

Olubuyide³

1979

Can. J. Chem.

View full text Add to dashboard Cite

JIDE IGE, J. FOLORUNSO OJO, and OLUSEGUN OLUBUYIDE. Can. J. Chem. 57.2065Chem. 57. (1979. The rates of the oxidation of tris-(1,lO-phenanthroline)iron(II) by chlorine and bromine, and of the reduction of tris-(1,lO-phenanthroline)iron(III) by iodide ions have been measured at ionic strength I = 1.0 mol dm-3 (LiCIO,). All the reactions obey second-order rate law:The activation parameters for the reactions are: Fe(Phen)32+/Br,: AH* = (64.2 + 3.2) kJ mol-', AS* = -(24.9 + 1.5) J mol-' K-'. Fe(Phen)33+/I-:AH* = (39.8 t 2.1) kJ mol-', AS* = -(19.7 + 0.8) J mol-I K-'.The reactions of tris-(1,lO-phenanthroline)iron(II) with chlorine and bromine are unaffected by chloride, bromide, and acid. The proposed mechanism for these reactions involves a series of one-electron changes, with the species X,-(X = CI, Br) as reaction intermediates, since good linear free energy correlations for the primary step, resulting in the formation of X2-, are obtained. The reduction of tris-(1,lO-phenanthroline)iron(III) by iodide ions is catalysed by bromide and chloride ions, whereas the reduction of aquoiron(II1) by iodide ions is known to be inhibited by bromide and chloride ions. A mechanistic interpretation of this observation is suggested. [Traduit par le journal]

show abstract

Section: Discussionsupporting

confidence: 58%

Kinetics and mechanism of oxidation of tris-(1,10-phenanthroline)iron(II) by chlorine and bromine and of the reduction of tris-(1,10-phenanthroline)iron(III) by iodide ions

Ige¹,

Ojo²,

Olubuyide³

1979

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…As a first step in addressing these questions the present paper reports on the oxidation of TGA by [Mo(CN) 8 ] 3- . The reactions of the octacyanomolybdate(V) anion with inorganic substrates have been well documented, − and its use as an outer-sphere oxidant is well established. Olatunji et al have reported on the reduction of this complex by a series of three aliphatic thiols: l -cysteine, penicillamine, and thioglycolic acid .…”

Section: Introductionmentioning

confidence: 99%

Reduction of Octacyanomolybdate(V) by Thioglycolic Acid in Aqueous Media

2002

View full text Add to dashboard Cite

In aqueous media at 25 degrees C [Mo(CN)(8)](3-) is reduced by thioglycolic acid (HSCH(2)COOH, TGA), and the reaction is strongly accelerated by the presence of trace amounts of copper ions. Dipicolinic acid (dipic) is an effective inhibitor of the copper catalysis. Both with and without dipic the reaction has the stoichiometry 2[Mo(CN)(8)](3-) + 2TGA --> 2[Mo(CN)(8)](4-) + RSSR, where RSSR is the disulfide derived from formal oxidative dimerization of TGA. In the presence of dipic, PBN (N-tert-butyl-alpha-phenyl-nitrone), and with a large excess of TGA the rate law for consumption of [Mo(CN)(8)](3-) is first order in both [TGA] and [Mo(CN)(8)(3-)]. The complex pH dependence is consistent with (-)SCH(2)CO(2)(-) being highly reactive (k = 1.8 x 10(4) M(-1) s(-1)), the monoanion being less reactive, and HSCH(2)CO(2)H being unreactive. A mechanism is proposed in which the dianion undergoes electron transfer to [Mo(CN)(8)](3-), thus generating the thiyl radical. Analysis of the electron-transfer rate constant in terms of Marcus theory yields an effective self-exchange rate constant for the thiolate/thiyl redox couple that is in reasonable agreement with the value derived previously from the reaction of TGA with [IrCl(6)](2-). When copper catalysis is inhibited, the two reactions differ substantially in that the yield of (-)O(3)SCH(2)CO(2)(-) is significant for [IrCl(6)](2-) but undetectable for [Mo(CN)(8)](3-).

show abstract

“…A similar lack of variation of rate with [SO4'-] has also been observed (3). The ionic strength effects parallel those of the reactions of iodide with 12-tungstocobaltate(1II) (11) and with octacyanomolybdate(V) (12). In the latter system, the study at low ionic strength (I 5 0.01 M ) has suggested that ion pairs may not play an important role in this reaction.…”

Section: Oxidation Oj' Iodide By /?En-clchloroirid~zte(1v) Reaction Imentioning

confidence: 71%

“…For other oxidants, however, (Co(III),, (lo), Cu(II1) peptide (9), Mo(CN)? (12), and 12-tungstocobaltoate(III) (1 1 ) ) only a first order term in iodide is observed.…”

Section: Oxidation Oj' Iodide By /?En-clchloroirid~zte(1v) Reaction Imentioning

confidence: 96%

Initial state and transition state solvation effects in the oxidation of iodide and catechol by hexachloroiridate(IV) in binary aqueous solvent mixtures

Blandamer¹,

Burgess²,

Hamshere³

et al. 1983

Can. J. Chem.

View full text Add to dashboard Cite

. 61, 1361 (1983). Rate constants arc rcportcd for hexachloroiridate(IV) oxidation of iodidc in methanol-, cthanol-, t-butyl alcohol -, cthylene glycol-, glycerol-, acetone-, acetonitrile-, and dimcthyl sulphoxidc -water solvent mixtures, and for thc hcxachloroiridate(1V) oxidation of catcchol in methanol-watcr mixtures. With thc aid of ancillary solubility data and measurements, solvent effects on reactivity have been analysed into initial statc and transition statc components. In the lattcr, there arc probably both electron transfer and diffusion contributions since it is not possiblc to identify uniquely the separate kinetic steps associated with the activation process. In these redox systems, however, transition state solvation changes dominate. This conclusion is compared with initial state -transition state effects in the reaction of catechol with hexahydroxoantimonic acid, in the bromate oxidation of bromide, the peroxodisulphate oxidation of iodide, and with patterns established earlicr for substitution at inorganic centres. In view of some disagreements and uncertainties in the literature concerning the number of molecules of water of crystallisation in potassium hexachloroiridate(II1) and hexachloroiridate(1V). this matter, of considcrable importance to hexachloroiridate transfer parameter estimation, is briefly reviewed.

show abstract

The kinetics of the oxidation of iodide ions by octacyanomolybdate(V) ions in aqueous solution

Cited by 21 publications

References 0 publications

Kinetics and mechanism of oxidation of tris-(1,10-phenanthroline)iron(II) by chlorine and bromine and of the reduction of tris-(1,10-phenanthroline)iron(III) by iodide ions

Kinetics and mechanism of oxidation of tris-(1,10-phenanthroline)iron(II) by chlorine and bromine and of the reduction of tris-(1,10-phenanthroline)iron(III) by iodide ions

Reduction of Octacyanomolybdate(V) by Thioglycolic Acid in Aqueous Media

Initial state and transition state solvation effects in the oxidation of iodide and catechol by hexachloroiridate(IV) in binary aqueous solvent mixtures

Contact Info

Product

Resources

About