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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of ligand substitution reactions of NiL and Ni2L with cyanide ion (L = hexamethylenediaminetetraacetic acid) (1986)
    Springer
    Transition metal chemistry 11 (1986), S. 11-15 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The kinetics and mechanism of reactions of cyanide ion with [NiL] and [Ni2L] (L = hexamethylenediaminetetraacetic acid) have been studied spectrophotometrically at 25 ±0.1 °C, with pH=11.0±0.02, and I=0.1 M(NaClO4). In both reactions the final product was [Ni(CN)4]2−. The order with respect to [CN−] was found to be one over a wide range of cyanide ion concentrations for both the systems. In the Ni2L-CN− system, however, the reaction becomes zero order with respect to cyanide when [CN−]〈6×10−4 M.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01064493
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetic and mechanism of pentacyanohydroxoferrate(III) formation from the reaction of [Fe2HPDTA(OH)2] with cyanide ions (1987)
    Springer
    Transition metal chemistry 12 (1987), S. 261-264 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The kinetics and mechanism of exchange of HPDTA in [Fe2HPDTA(OH)2] with cyanide ion (HPDTA=2-hydroxytrimethylenediaminetetraacetic acid) was investigated spectrophotometrically by monitoring the peak at 395 nm (λ max of [Fe(CN)5OH]3− at pH=11.0±0.02,I=0.25m (NaClO4) at ±0.1°C). Three distinct observable stages were identified; the first is the formation of [Fe(CN)5OH]3−, the second the formation of [Fe(CN)6]3− from it and the third the reduction of [Fe(CN)6]3− to [Fe(CN)6]4− by HPDTA4− released in the first stage. The first stage follows first-order kinetics in [Fe2HPDTA(OH)2] and second-order in [CN−] over a wide range of [CN−], but becomes zero order at [CN−]〈5×10−2 m. We suggest a cyanide-independent dissociation of [Fe2HPDTA)(OH)2] into [FeHPDTA(OH)] and [Fe(OH)]2+ at low cyanide concentrations and a cyanide-assisted rapid dissociation of [Fe2HPDTA(OH)2] to [FeHPDTA(OH)(CN)]3− and [Fe(OH)]2+ at higher cyanide concentrations. The excess of cyanide reacts further with [FeHPDTA(OH)(CN)]3− finally to form [Fe(CN)5OH]3−. The reverse reaction between [Fe(CN)5OH]3− and HPDTA4− is first-order in [Fe(CN)5OH]3− and HPDTA4−, and exhibits inverse first-order dependence on cyanide concentration. A six-step mechanism is proposed for the first stage of reaction, with the fifth step as rate determining.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01023544
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of ligand substitution of mono(polyamine)-nickel(II) complexes with 4-(2-pyridylazo)resorcinol (1991)
    Springer
    Transition metal chemistry 16 (1991), S. 511-517 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The kinetics and mechanism of ligand substitution reactions of tetraethylenepentamine nickel(II), Ni (Teren), and triethylenetetraamine nickel(II), Ni(Trien), with 4-(2-pyridylazo)resorcinol (parH2) have been studied spectrophotometrically at I=0.1 M (NaClO4) at 25°C. In both systems two distinct reaction steps are observed. The rapid first step follows the rate law d[Ni(Polyamine)(ParH2)]/dt=k1 [Ni(Polyamine)] [ParH2]. The formation of ternary complexes of Ni (Polyamine) with ParH2 has been investigated under second order equal concentration conditions. The values of second order rate constants for the Trien and Teren reactions are (2.1±0.2)×104 M−1s−1 and (7.8±0.6)×103 M−1s−1 respectively at pH=9.0, I=0.1 M and 25°C. The rate law for the second step may be written as d[Ni(Par)2]/dt=k2[Ni(Polyamine)(ParH2)]. Values of k2 for the Trien and Teren systems are (2.5±0.1)×10−4 s−1 and (4.76±0.3)×10−5 s−1 respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01024320
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  • 4
    Electronic Resource
    Electronic Resource
    An independent kinetic and mechanistic study of the secondary reactions in the substitution of [FeL(OH)](n−2)− (L= triethylenetetraaminehexaacetic acid) by cyanide ions (1990)
    Springer
    Transition metal chemistry 15 (1990), S. 58-62 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The kinetics of reaction between [Fe(CN)5OH]3− and CN− have been investigated spectrophotometrically at pH=11.00, I=0.25 M(NaClO4) and temp.=25.0°C by disappearance of the absorption peak at 395 nm. The rate data for this reaction followed first order kinetics in both [Fe(CN)5OH3−] and [CN−]. The second order rate constant (kf) was found to be (3.44±0.08)×10−3 M−1 s−1. The pH dependence of the reaction was also investigated in the range 9–12. The activation parameters were found to be ΔH†=36.4kJ mol−1 and ΔS†=−168JK−1 mol−1. The reaction between [Fe(CN)6]3− and TTHA6− (TTHA=triethylenetetraaminehexaacetic acid) has also been followed spectrophotometrically at 420 nm, pH=11.00, I=0.1M (NaClO4) and temp.=25.0°C. This reaction also followed first order kinetics in both [Fe(CN) 6 3− ] and [TTHA6−]. The second order rate constant (kf) was found to be (3.74±0.21)×10−2 M−1 s−1. The rate of reaction was found to increase with pH in the range 9–11.5. The different reactive species of TTHA (L) are H2L4− HL5− and L6−. The rate constants for these species have been calculated and the pH profile is explained. The values of the activation parameters were found to be ΔH†= 30.9 kJmol−1 and ΔS†=−167JK−1 mol−1. Electron transfer from [Fe(CN)6]3− to the substrate followed by decomposition of the latter is proposed. The oxidation products of TTHA have been investigated by g.l.c.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01032233
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of pentacyanohydroxoferrate(III) formation from the reaction of cyanide ion with [Fe2L(OH)2]2− (L=triethylenetetraaminehexaacetate) (1986)
    Springer
    Transition metal chemistry 11 (1986), S. 337-342 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The kinetics and mechanism of the reaction between [Fe2L(OH)2]2− and cyanide ion (L = TTHA, triethylenetetraaminehexaacetate) have been studied spectrophotometrically atpH=11.0±0.1,I=0.1 M(NaClO4) and T = 25±0.1 °C. The overall reaction consists of three distinct, observable stages. The first stage involves the dissociation of the binuclear complex into a mononuclear complex [FeL(OH)]4− which then reacts with cyanide to form [Fe(CN)5OH]3−. The species [Fe(CN)5OH]3− reacts further with an excess of cyanide and forms [Fe(CN)6]3− in the second stage of reaction. The last stage involves the reduction of [Fe(CN)6]3− formed in the second stage by the TTHA6− released in the first stage of reaction. The formation of [Fe(CN)5OH]3− in the first stage is firstorder in [Fe2L(OH)2]2− and third-order in cyanide over a large range of cyanide concentrations but becomes zero-order in cyanide at [CN−] 〈 4×10−2M. These observations enable us to suggest the presence of a slow step in which [Fe2L(OH)2]2− dissociates into [FeL(OH)]4− and [FeOH]2+ at low cyanide concentrations and a cyanide assisted rapid dissociation of [Fe2L(OH)2]2− to [FeL(OH)(CN)]5− at higher cyanide concentrations. The species [FeL(OH)(CN)]5− reacts further with an excess of cyanide to produce [Fe(CN)5OH]3− finally. The reverse reaction between [Fe(CN)5OH]3− and TTHA6− follows first-order dependence in each of [Fe(CN)5OH]3− and TTHA6− and inverse first-order dependence on cyanide concentration. A six-step mechanism has been proposed for the first stage of reaction in which the fifth has been identified as the rate-determining step.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00621518
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  • 6
    Electronic Resource
    Electronic Resource
    The kinetics and mechanism of reaction between ethylenediaminetetraacetomanganate(III) and cyanide ion (1988)
    Springer
    Transition metal chemistry 13 (1988), S. 267-271 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The title reaction has been followed spectrophotometrically at 325 nm (λmax of [Mn(CN)6]3−) under pseudo-first order conditions with cyanide in a large excess at pH=10.0, I=0.1M (NaClO4) and 25°C. The reaction follows first-order kinetics in [MnEDTA(OH)]2− and exhibits variable-order dependence in [CN−] one at high cyanide concentration, and two at low cyanide concentration. The product of above reaction has been identified as [Mn(CN)6]3−. The kinetics of the reverse reaction,i.e., the reaction of [Mn(CN)6]3- with EDTA4− have also been followed spectrophotometrically. This reactions is first-order with respect to both [Mn(CN) 6 3− ] and [EDTA4−] and exhibits an inverse first-order dependence on [CN−]. A six-step mechanism has been proposed in which the penultimate step is rate-determining. The activation parameters have been obtained and support the postulated mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01025671
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  • 7
    Electronic Resource
    Electronic Resource
    Linear free energy relationships and kinetics of ligand substitutions: Correlations of rate constants with overall stability constants of reactive intermediate species in the stepwise formation of pentacyanohydroxoferrate(III) from monohydroxoaminocarboxylato iron(III) complexes (1985)
    Springer
    Transition metal chemistry 10 (1985), S. 220-223 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A linear free energy relationship has been proposed between stepwise rate constants and the overall stability constants of the intermediates of the type FeL(OH)(CN)x (where x=0, 1, 2 and 3) formed in the five step reaction mechanism of CN− with FeLOH, where L denotes aminocarboxylatesviz. EDTA, HEDTA and DTPA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692632
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of pentacyanohydroxoferrate(III) formation from mono(aminocarboxylato)iron(III) complexes (1985)
    Springer
    Transition metal chemistry 10 (1985), S. 227-232 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The kinetics and mechanism of the system: [FeL(OH)]2−n + 5 CN− ⇌ [Fe(CN)5(OH)]3− + Ln−, where L=DTPA or HEDTA, have been investigated at pH= 10.5±0.2, I=0.25 M and t=25±0.1
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692634
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