Kinetics and mechanism of the aquation of the trinuclear cation, [μ3-oxo-triaqua-hexakis(acetato)tris(iron(III))]+in perchloric acid media

Maragh, Paul T.; Thomas, Sonia E.; Dasgupta, Tara P.

doi:10.1016/j.ica.2005.07.011

Cited by 14 publications

(7 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The The magnitude of the intercept is far greater than the values deduced for the rate of the spontaneous decomposition (water hydrolysis) or the acid-assisted hydrolysis of the complex [19]. As noted previously, this rapid step does not involve electron transfer and is thus suggestive of an equilibrium process.…”

Section: Kinetic Resultsmentioning

confidence: 60%

“…This is accompanied by an increase in the charge transfer (CT) character of the iron(III) centre. The pH investigations were limited to medium pH ranges since at low pH, the carboxylate bridges protonate, acid hydrolysis [19] occurs absorbance change. Extrapolation is required for a determination of the initial absorbance of the complex solution, as the pH is decreased.…”

Section: Resultsmentioning

confidence: 99%

“…The second step is noted by a less rapid increase in the absorbance at 550 nm ( From an analysis of the kinetic data at the ends of the buffer range from a 1:1 stoichiometric reaction mixture between L-ascorbic acid and the complex, the intercept observed (k 0 ) for each temperature for the variation of [H 2 A] T and pH is due to a combination of the spontaneous decomposition (water hydrolysis) and the acid hydrolysis of the complex [19]. The observed rate constants for the electron transfer process show a non-linear increase with an increase in pH ( Table 2) (Online Resource 4).…”

Section: Kinetic Resultsmentioning

confidence: 99%

“…The stability of the [Fe 3 O(CH 3 -CO 2 ) 6 (H 2 O) 3 ] ? complex cation in aqueous perchloric acid media has been investigated by Maragh et al [19]. Our laboratory has shown that these iron-containing oxo-centred trinuclear acetate complexes have an inherent instability in an aqueous environment and are susceptible to water-and acid-assisted hydrolysis [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…complex cation in aqueous perchloric acid media has been investigated by Maragh et al [19]. Our laboratory has shown that these iron-containing oxo-centred trinuclear acetate complexes have an inherent instability in an aqueous environment and are susceptible to water-and acid-assisted hydrolysis [19,20]. Following on the work done on the aqueous chemistry of this complex, we embarked on detailed investigations of the electron transfer processes involving the [Fe 3 O(CH 3 CO 2 ) 6 (H 2 O) 3 ] ?…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Mechanistic studies on the intramolecular electron transfer in an adduct species of the oxo-centred trinuclear iron(III) cation and l-ascorbic acid in aqueous solution

Lawrence

Thomas

Maragh

et al. 2011

Transition Met Chem

Self Cite

View full text Add to dashboard Cite

The kinetics of the intra-molecular electron transfer of an adduct of L-ascorbic acid and the [Fe 3 III O(CH 3 -COO) 6 (H 2 O) 3 ] ? cation in aqueous acetate buffer was studied spectrophotometrically, over the ranges 2.55 B pH B 3.74, 20.0 B h B 35.0°C, at an ionic strength of 0.50 and 1.0 mol dm -3 (NaClO 4 ). The reaction of L-ascorbic acid and the complex cation involves the rapid formation of an adduct species followed by a slower reduction in the iron centres through consecutive one-electron transfer processes. The final product of the reaction is aqueous iron(II) in acetate buffer. The proposed mechanism involves the triaqua and diaqua-hydroxo species of the complex cation, both of which form adducts with L-ascorbic acid. At 25°C, the equilibrium constant for the adduct formation was found to be 86 ± 15 and 5.8 ± 0.2 dm 3 mol -1 for the triaqua and diaquahydroxo species, respectively. The kinetic parameters derived from the rate expression have been found to be: k 0 = (1.12 ± 0.02) 9 10 -2 s -1 for the combined spontaneous decomposition and k 1 = (4.47 ± 0.06) 9 10 -2 s -1 (DH 1 à = 51.0 ± 2.3 kJ mol -1 , DS 1 à = -100 ± 8 J K -1 mol -1 ), k 2 = (4.79 ± 0.38) 9 10 -1 s -1 (DH 2 à = 76.5 ± 0.8 kJ mol -1 , DS 2 à = 6 ± 3 J K -1 mol -1 ) for the triaqua and diaqua-hydoxo species, respectively. Abbreviation Trimer [Fe 3III O(CH 3 COO) 6 (H 2 O) 3 ] ?

show abstract

Section: Kinetic Resultsmentioning

confidence: 60%

Section: Resultsmentioning

confidence: 99%

Section: Kinetic Resultsmentioning

confidence: 99%