Kinetics and mechanism of the oxidation of diethylenetriaminepentaacetatocobaltate(II) by periodate

Abu-Elenien, Mervat H.; AL-SHATTI, N. I.; Hussein, Mohamed Ali; Sulfab, Yousif

doi:10.1016/s0277-5387(00)84252-7

Cited by 11 publications

(10 citation statements)

References 12 publications

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“…The I VI in the initial product is probably substitutional by water at a very slow rate due to the substituted inertness of Co III and also the Co II -OIO 3 bond being stronger than Co-H 2 O bond. The oxidation of cobalt(II) complexes of propylenediaminetetraacetate (PDTA) [20], 1,3-diamino-2-hydroxypropanetetraacetate (HPDTA) [20], diethylenetriamine-pentaacetate (DPTA) [21], trimethylenediaminetetraacetate (TMDTA) [22] and ethyleneglycol,bis(2-aminoethyl)ether,N,N,N 0 ,N 0 -tetraacetate (EGTA) [22] by periodate gave only the final product.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of periodate oxidation of two ternary nitrilotriacetatochromium(III) complexes involving histidine and aspartate co-ligands

Ewais

Habib²,

Elroby

2009

Transition Met Chem

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The oxidation of [Cr III (HNTA)(Hist)(H 2 O)] -and [Cr III (HNTA)(Asp)(H 2 O)] -(NTA = nitrilotriacetate, Hist = L-histidinate and Asp = DL-aspartate) by periodate in aqueous medium has been studied spectrophotometrically between 15.0 and 35.0°C under pseudo-first-order conditions, [IO 4 -] ) [complex]. The rate increases over the pH range 3.40-4.45 in both cases, but the two complexes give different rate laws. It is proposed that electron transfer proceeds through an inner-sphere mechanism via coordination of IO 4 -to chromium(III). A common mechanism for the oxidation of some chromium(III) complexes by periodate is proposed, and this is supported by an excellent isokinetic relationship between DH* and DS* values for these reactions.

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Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of periodate oxidation of two ternary nitrilotriacetatochromium(III) complexes involving histidine and aspartate co-ligands

Ewais

Habib²,

Elroby

2009

Transition Met Chem

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“…(9), (10) and (11) 6 ] 4-were found to be 0.16 ± 0.02 and 0.012 ± 0.01 M -1 s -1 , respectively. The evaluated value of k 1 is in good agreement with experimentally found value of a second order rate constant (k).…”

Section: Effect Of [Fe(cn) 6 ] 4-on Rate Of Oxidation Of [Fe(cn) 6 ] mentioning

confidence: 92%

“…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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“…In all such cases the [IO − 4 ] is believed to get reduced to [IO − 3 ] following an inner-sphere electron transfer mechanism. The periodate oxidation of [Co(II)L] 2−n (L= EDTA) [10], (HEDTA) and (EDDA) [11], (CYDTA) [12], (NTA) [13], (DTPA) [14], (PDTA) and (HPDTA) [15] by periodate ion has been the subject of investigation until recently of several investigators including us [15] and believed to proceed through inner-sphere mechanism via formation of inner-sphere complexes of the type [LCo(II)-OIO 3 ] 1−n and [LCo(II)-(OIO 3 ) 2 ] −n which eventually get converted slowly producing corresponding [Co(III)L] 3−n complexes as final reaction product. The previous studies on periodate oxidation of V(IV) [5], Fe(II) [6] and Cr(III) and recent studies on Cr(III) [16][17][18][19][20][21][22][23] are also found to proceed via an inner-sphere electron transfer pathway.…”

Section: Introductionmentioning

confidence: 99%

“…It was earlier proposed that the oxidations by periodate ion generally proceed via an innersphere mechanism [4][5][6][7][10][11][12][13][14][15], Hence, the oxidation process involving second order dependence in [IO − 4 ], probably also proceeds via an innersphere electron pathway. .…”

mentioning

confidence: 99%

The Kinetics and Mechanism of Oxidation of Triethylenetetraaminehexaacetatocobaltate(II) Complex by Periodate Ion in AqueousMedium

Naik¹,

Srivastava²,

Verma³

et al. 2007

BioInorganic Reaction Mechanisms

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The kinetics and mechanism of oxidation of [Co(II)TTHA] 4− (where TTHA =Triehylenetetraaminehexaaceticacid) by periodate ion has been studied in aqueous acidic medium. The reaction has been investigated spectrophotometrically at λ max = 550 nm under pseudo-first-order condition by taking large excess of oxidant, [IO − 4 ] at pH = 4.0+0.02, I = 0.1 M (CH 3 COONa + NaNO 3 ) and at three different temperatures viz. 15 • C, 20 • C and 25 • C. The electron transfer reaction between [Co(II)TTHA] 4− and [IO − 4 ] obeys inner-sphere reaction pathway through the formation of long-lived intermediate complex which eventually get converted into a corresponding [Co(III)TTHA] 3− complex as final reaction product. The experimental observations have shown that the reaction exhibit first-order dependence in [Co(II)TTHA] 4− . The variation of pseudo-first-order rate constant (k obs ) with [IO − 4 ] keeping other reaction variables fixed at constant value is found to obey the following emperical equation.This rate law is consistent with a three step mechanistic scheme. The values of k obs are almost invariant with increasing pH and attributed due to the reaction of deprotonated form of [Co(II)TTHA] 4− complex and in the whole pH region. Eyring's equations has been used to calculate the activation parameters and found to be H # = 16.63 kJ mole −1 ; S # = -214.00 JK −1 mole −1 . These values are consistent with three step mechanistic scheme as proposed.

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Kinetics and mechanism of the oxidation of diethylenetriaminepentaacetatocobaltate(II) by periodate

Cited by 11 publications

References 12 publications

Kinetics and mechanism of periodate oxidation of two ternary nitrilotriacetatochromium(III) complexes involving histidine and aspartate co-ligands

Kinetics and mechanism of periodate oxidation of two ternary nitrilotriacetatochromium(III) complexes involving histidine and aspartate co-ligands

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

The Kinetics and Mechanism of Oxidation of Triethylenetetraaminehexaacetatocobaltate(II) Complex by Periodate Ion in AqueousMedium

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