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Mansour, Mohamed A.

doi:10.1023/a:1022966528585

Cited by 5 publications

(6 citation statements)

References 8 publications

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“…A similar type of inner sphere electron transfer process was also observed in the reaction of periodate ions with aqua-ions of V(IV) [2], Fe(II) [4], and Cr(III) [11]. The recent studies on the VO 2 + oxidation of [Co II L(H 2 O)] 2-n [L = HEDTA and EDTA] [12][13] have further revealed the formation of an intermediate which converted slowly to penta-co-ordinated [Co III L(H 2 O)] 3-n as final reaction product and provides additional support to the proposed mechanistic scheme (vide supra) for the reacting system at hand. Therefore, as an attempt to verify the consistency in the kinetics of oxidation of amine-N-polycarboxylates complexes of Co(II) by periodate ions.…”

Section: Introductionsupporting

confidence: 53%

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Kinetic and mechanistic studies of oxidation of amine-N-polycarboxylates complexes of cobalt(II) by periodate ions in aqueous medium

Naik

Srivastava

Tiwari

et al. 2007

JICS

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The kinetics and mechanism of interaction of periodate ion with [Co II L(H 2 O)] 2-n [L = trimethylenediaminetetraaceticacid (TMDTA)] and ethylene glycol bis(2-aminoethyl ether) N,N,N',N'-tetraaceticacid (EGTA) have been studied spectrophotometrically by following an increase in absorbance at λ max = 550 nm in acetate buffer medium as a function of pH, ionic strength, temperature, various concentration of periodate and [Co II L(H 2 O)] 2-n under pseudo-first order conditions. The experimental observations have revealed that the intermediates having sufficiently high half life are produced during the course of both the reactions which finally get converted into a corresponding [Co III L(H 2 O)] 3-n complexes as a final reaction product. The reaction is found to obey the general rate law Rate = (k 2 [IO 4 -] + k 3 [IO 4 -] 2 ) [Co II L(H 2 O)] 2-n . This rate law is consistent with a four step mechanistic scheme (vide supra) where electron transfer proceeds through an inner sphere complex formation. The value of rate constant k 2 is independent of pH over the entire pH range which suggest that unprotonated form of [Co II L(H 2 O)] 2-n is the only predominant species. The value of k 2 is invariant to ionic strength variation in both the systems. The value of k 3 is also found to be almost invariant to ionic strength in case of [Co II TMDTA(H 2 O)] 2--[IO 4 ] -system but it decreases considerably in case of [Co II EGTA(H 2 O)] 2--[IO 4 ] -system with the corresponding decrease in ionic strength. The activation parameters have been computed and given in support of proposed mechanistic scheme.

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Section: Introductionsupporting

confidence: 53%

“…Comparison of equations (6) and (10) gives: (4) and (5) are to be considered simultaneously as the rate determining step for the second pathway of reaction and the rate law is given by equation (12).…”

Section: Effect Of Complex Concentration On Reaction Ofmentioning

confidence: 99%

Kinetic and mechanistic studies of oxidation of amine-N-polycarboxylates complexes of cobalt(II) by periodate ions in aqueous medium

Naik

Srivastava

Tiwari

et al. 2007

JICS

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“…The [CoHEDTAOH 2 ] − complex was prepared according to the method of Mansour [17] and was characterized using UV/Visible. The UV/Visible spectrum of [CoHEDTAOH 2 ] − was scanned between wavelength ranges of 350 -600 nm and gave λ max of 510 nm.…”

Section: Methodsmentioning

confidence: 99%

Kinetics and Stoichiometry of the Reduction of Hydrogen Peroxide by an Aminocarboxylactocobaltate(II) Complex in Aqueous Medium

Onu¹,

Iyun²,

Idris³

2015

OJIC

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The kinetics and stoichiometry of the reduction of H2O2 by an aminocaboxylactocobaltate(II) complex (hereafter[CoHEDTAOH2] −) in aqueous medium have been studied under the following conditions: T = 29˚C ± 1˚C, Ionic Strength, I = 0.50 mol dm −3 (NaClO4), [H + ] = 1 × 10 −3 mol dm −3. The ratio from the stoichiometric study conforms to the equation 2[CoHEDTAOH2] − + H2O2 + 2H + → 2 [Co-HEDTAOH2] + 2H2O. The rate of reaction varied linearly to the first power of the concentrations of the reductant and oxidant and displayed inverse dependence on acid concentration. The plot of acid dependent rate constant versus [H + ] −1 was linear with zero intercept. The [CoHEDTAOH2] −-H2O2 reaction was insensitive to the change in ionic strength of the medium suggesting interaction of charged and uncharged species at the activated complex. The Michaelis-Menten plot of [ ] 1 1 1 versus k oxidant was linear without intercept which suggested absence of intermediate complex. Evidences in this paper showed that the reaction occurred through the outer-sphere mechanism.

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“…The periodate oxidation of several inorganic and organic substrate takes place through either inner sphere or outer sphere mechanism. The periodate oxidation of [M IV (CN) 8 ] 4-(M = W or Mo) [6][7] and some polyaminocarboxylato complexes of Co(II) [8][9][10][11][12][13], V(IV) [14], Fe(II) [15] and Cr(III) [16][17][18] proceeds through an inner sphere electron transfer pathway.…”

Section: Introductionmentioning

confidence: 99%

The kinetics and mechanism of oxidation of hexacyanoferrate(II) by periodate ion in highly alkaline aqueous medium

Naik

Srivastava

Asthana

2008

JICS

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The oxidation of hexacyanoferrate(II) by periodate ion has been studied spectrophotometrically by registering an increase in absorbance at 420 nm ( max of yellow colored [Fe(CN) 6 3-] complex under pseudo first-order conditions by taking excess of [IO 4 -] over [Fe(CN) 6 4-]. The reaction conditions were: pH = 9.5 ± 0.02, I = 0.1 M (NaCl) and Temp. = 25 ± 0.1 ºC. The reaction exhibited first-order dependence on each [IO 4 -] and [Fe(CN) 6 4-]. The effects of variations of pH, ionic strength and temperature were also studied. The experimental observations revealed that the periodate ion exists in its protonated forms viz. [H 2 IO 6 ] 3-and [H 3 IO 6 ] 2-while [Fe(CN) 6 ] 4-is present in its deprotonated form throughout the pH region selected for the present study. It has also been observed that deprotonated form of [Fe(CN) 6 4-] and protonated forms of periodate ion are the most reactive species towards oxidation of [Fe(CN) 6 4-]. The repetitive spectral scan is provided as an evidence to prove the conversion of [Fe(CN) 6 4-] to[Fe(CN) 6 3-] in the present reaction. The activation parameters have also been computed using the Eyring's plot and found to be, H ‡ = 51.53 ± 0.06 kJ mol -1 , S ‡ = -97.12 ± 1.57 J K -1 mol -1 and provided in support of a most plausible mechanistic scheme for the reaction under study.

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Untitled

Cited by 5 publications

References 8 publications

Kinetic and mechanistic studies of oxidation of amine-N-polycarboxylates complexes of cobalt(II) by periodate ions in aqueous medium

Kinetic and mechanistic studies of oxidation of amine-N-polycarboxylates complexes of cobalt(II) by periodate ions in aqueous medium

Kinetics and Stoichiometry of the Reduction of Hydrogen Peroxide by an Aminocarboxylactocobaltate(II) Complex in Aqueous Medium

The kinetics and mechanism of oxidation of hexacyanoferrate(II) by periodate ion in highly alkaline aqueous medium

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