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Maji, Dilip; Banerjee, Rupendranath

doi:10.1023/a:1011017706307

Cited by 11 publications

(5 citation statements)

References 15 publications

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“…The reaction shown in Eq. (16) is thus much preferred for the formation of Mn III Mn IV intermediate [50]. Stepwise one-electron transfer and retention of nuclearity as proposed above are supported by the fact that different oxidation levels of the binuclear catalase enzyme models preserve nuclearity [51], the various oxidation levels (S states) of the manganese cluster in PSII also apparently retain bond connectivity [2] and high valent manganese has a propensity to form (μ-oxo) complexes in weakly acidic media [52].…”

Section: [Mn 3 (μ-O) 4 (Phen) 4 (H 2 O) 2 ] 4+ + 3rcocoohmentioning

confidence: 99%

Mechanistic studies on the oxidation of glyoxylic and pyruvic acids by a {Mn₃O₄}⁴⁺ core in aqueous media

Mandal

Das

Mukhopadhyay

2010

Int J of Chemical Kinetics

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In aqueous media, the Mn IV trimer [Mn IV 3 (μ-O) 4 (phen) 4 (H 2 O) 2 ] 4+ (1, phen = 1,10phenanthroline) equilibrates with its deprotonated from [Mn 3 (μ-O) 4 (phen) 4 (H 2 O)(OH)] 3+ (2). Among the several synthetic multinuclear oxo-and/or carboxylato-bridged manganese complexes known to date containing metal-bound water, to the best of our knowledge, 1 is one of the rare examples that deprotonates (1 2 + H + ; pK a = 4.00 (±0.15) at 25.0 • C, I = 1.0 mol dm −3 , maintained with NaNO 3 ) at physiological pH. In aqueous media (pH 2-4), 1 oxidizes both glyoxylic and pyruvic acids to formic and acetic acid, respectively, along with the formation of CO 2 , the end manganese state being Mn II . Kinetic studies suggest that the species 1, its deprotonated form 2, the reducing acids (HA), and their conjugate bases (A − ) all take part in the reaction. The oxidant 1 is found to be more reactive than its conjugate base 2, and HA reacts faster than A − in reducing 1 or 2. The gem-diol form of the α-oxo acids (especially for glyoxylic acid) is the possible reducing species. The Mn IV 3 to Mn II transition in the present observation proceeds through the intermediate generation of the spectrally characterized mixed-valent Mn III Mn IV dimer that quickly collapses to Mn II . The observed rates of glyoxylic or pyruvic acid oxidation do not depend on the variation of 1,10-phenanthroline content of the solution, indicating the absence of any phen-releasing preequilibrium of the title complex in solution. The reactions rates were found to be lowered in media enriched with D 2 O in comparison to that in H 2 O and a rate-limiting one electron one proton (1e, 1H + ) electroprotic mechanism is proposed. C

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Section: [Mn 3 (μ-O) 4 (Phen) 4 (H 2 O) 2 ] 4+ + 3rcocoohmentioning

confidence: 99%

Mechanistic studies on the oxidation of glyoxylic and pyruvic acids by a {Mn₃O₄}⁴⁺ core in aqueous media

Mandal

Das

Mukhopadhyay

2010

Int J of Chemical Kinetics

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“…This type of biphasic kinetic profile has been simply described by a two‐step consecutive reaction scheme as shown in Eq. (2)

\begin{matrix} true \\ right normalA \overset{k_{1}}{\to} normalB \overset{k_{2}}{\to} normalC \end{matrix}

…”

Section: Resultsmentioning

confidence: 99%

“…(3) are interchangeable and they cannot be certainly associated with any particular reaction step in the reaction sequence (Eq. (2)) , for our convenience we associate k 1 and k 2 with the faster and slower reaction, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…With the help of Eq. (3), one can extract the rate constants from the plot of log 10 ( A t – A ∞ ) versus time data . In our present case, the reaction was monitored at 700 nm and the absorbance value at infinite time at this wavelength can be supposed to be zero since Fig.…”

Section: Resultsmentioning

confidence: 99%

“…(3) are interchangeable and they cannot be certainly associated with any particular reaction step in the reaction sequence (Eq. (2)) [60], for our convenience we associate k 1 and k 2 with the faster and slower reaction, respectively. Following this analytical method described herein, the rate constants k 1 and k 2 have been extracted from the data set associated with the kinetic runs.…”

Section: Analysis Of the Kinetic Datamentioning

confidence: 99%

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Kinetics and Mechanism of Oxidation of S₂O₃²⁻ by a Co‐Bound μ‐Amido‐μ‐Superoxo Complex

Singh

Das

Banerjee

et al. 2015

Int J of Chemical Kinetics

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In acetate buffer media (pH 4.5-5.4 2− ) and temperature (T), but it decreases with an increase in [H + ] and the ionic strength (I). Analysis of the log A t versus time data (A is the absorbance of 1 at time t) reveals that overall the reaction follows a biphasic consecutive reaction path with rate constants k 1 and k 2 and the change of absorbance is equal to {a 1 exp(-k 1 t) + a 2 exp(-k 2 t)}, where k 1 > k 2 .

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Kinetics and Mechanism of Oxidation of Fe²⁺ by the Tris(biguanide)manganese(IV) Ion in Aqueous Acid Media

et al. 2004

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Tris(biguanide)manganese(IV), [Mn(LH2)3]4+ (LH2 = biguanide, C2N5H7), quantitatively oxidises Fe2+ to Fe3+ and is itself reduced to Mn2+ with almost quantitative (> 95%) release of biguanide. The reaction rate strongly depends on added Fe3+; in the presence of externally added Fe3+, the reaction shows a clear first‐order dependence in [MnIV], whereas in the absence of any added Fe3+, an initial quick loss of MnIV is associated with a subsequent very sluggish decay. Two consecutive one‐electron transfer inner‐sphere steps are proposed for the entire redox process where [Mn(LH2)3]3+, the initial one‐electron‐reduced product of MnIV, is believed to be a steady‐state intermediate. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Untitled

Cited by 11 publications

References 15 publications

Mechanistic studies on the oxidation of glyoxylic and pyruvic acids by a {Mn₃O₄}⁴⁺ core in aqueous media

Mechanistic studies on the oxidation of glyoxylic and pyruvic acids by a {Mn₃O₄}⁴⁺ core in aqueous media

Kinetics and Mechanism of Oxidation of S₂O₃²⁻ by a Co‐Bound μ‐Amido‐μ‐Superoxo Complex

Kinetics and Mechanism of Oxidation of Fe²⁺ by the Tris(biguanide)manganese(IV) Ion in Aqueous Acid Media

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Untitled

Cited by 11 publications

References 15 publications

Mechanistic studies on the oxidation of glyoxylic and pyruvic acids by a {Mn3O4}4+ core in aqueous media

Mechanistic studies on the oxidation of glyoxylic and pyruvic acids by a {Mn3O4}4+ core in aqueous media

Kinetics and Mechanism of Oxidation of S2O32− by a Co‐Bound μ‐Amido‐μ‐Superoxo Complex

Kinetics and Mechanism of Oxidation of Fe2+ by the Tris(biguanide)manganese(IV) Ion in Aqueous Acid Media

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Mechanistic studies on the oxidation of glyoxylic and pyruvic acids by a {Mn₃O₄}⁴⁺ core in aqueous media

Mechanistic studies on the oxidation of glyoxylic and pyruvic acids by a {Mn₃O₄}⁴⁺ core in aqueous media

Kinetics and Mechanism of Oxidation of S₂O₃²⁻ by a Co‐Bound μ‐Amido‐μ‐Superoxo Complex

Kinetics and Mechanism of Oxidation of Fe²⁺ by the Tris(biguanide)manganese(IV) Ion in Aqueous Acid Media