A Polarographic Study of Mixed-ligand Complex Formation; Complexes of Copper and Cadmium with Oxalate Ion and Ethylenediamine

Schaap, Ward B.; McMasters, Donald L.

doi:10.1021/ja01484a003

Cited by 185 publications

(41 citation statements)

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“…A somewhat different comparison is also often made (13) of values of A log K = log KMAB -log KMA, <c=o which is the equilibrium constant for . This seems to be a common situation for copper bonded to 2,2'-bipyridyl and another chelating ligand attached through two oxygens (13)(14)(15), but negative values of A log K are also found when a ligand, other than 2,2'-bipyridyl, which chelates through nitrogen is used (16)(17)(18). In the present work, the values of A log K from Table 25 are…”

Section: Discussion Of Resultsmentioning

confidence: 56%

The Effect of Aromatic Amines on the Catalyzed Decarboxylation of 3-Oxo-glutaric Acid

Leong¹,

Lister²

1972

Can. J. Chem.

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Equilibrium constants have been measured for the formation of M A species, where M is divalent manganese, cobalt, nickel, or zinc, and A 2 -is the 3-0x0-glutarate ion. Equilibriumconstants havealso been measured for the reactions MB2' + A 2 -e M A B , where B is 2,2'-bipyridyl or 1,lO-phenanthroline. These constants were obtained by p H measurements at 25 "C and an ionic strength of 0.60. The results are compared with those for similar systems, especially as regards the tendency to form ternary mixed complexes of the type MAB.The rates of decarboxylation of the various M A and MAB species have been measured. The resulting rate constants follow the Irving-Williams order for stability constants, except that in both MAB species the cobalt compound decomposed slightly faster than the nickel compound. The aromatic base, which had been found earlier to have very little effect in copper complexes, increased the rate constants appreciably with other metals, especially with manganese and zinc. Usually 1,IO-phenanthroline has a larger effect than 2,2'-bipyridyl. Some possible explanations of the results are considered.Nous avons mesure les constantes d'equilibre dans la formation d'especes MA, ou M est le manganese, le cobalt, le nickel ou le zinc bivalents et A 2 -, I'ion 3-0x0-glutarate. Nous avons egalement mesure les constantes d'equilibre des reactions MB2' + A2-$MAB, oh B est le 2,2'-bipyridyl ou le 1 ,lo-phenanthroline. Ces constantes furent obtenues au moyen de mesures de p H a 25 "C et sous une force ionique de 0.60. Nous comparons les resultats Q ceux de systemes semblables, specialement en ce qui concerne la tendance a former des complexes ternaires mixtes du type MAB.Nous avons mesure les vitesses de dttcarboxylation des especes M A et MAB. Les constantes de vitesse obtenues suivent I'ordre d'Irving-Williams des constantes de stabilite, excepte que dans les deux especes MAB, le compose de cobalt se decompose Iegeremect plus vite que celui de nickel. La base aromatique, chez qui on a trouvk anterieurement tres peu d'effet dans les complexes de cuivre, augmente appreciablement les constantes de vitesse avec d'autres metaux, specialement le manganese et le zinc. La 1.10-phenanthroline possede un plus grand effet que le 7,2-bipyridyl. Nous considerons quelques explications possibles des rCsultats.[Traduit par le journal]Canadian Journal o f Chemistry, 50, 3573 (1972) In recent paper (I), the present authors reported experiments on the effect of two tertiary aromatic amines, 2,2'-bipyridyl and 1,lO-phenanthroline, on the decarboxylation of 3-0x0-glutaric acid, catalyzed by copper ions. It was found that complexes of formula CuAB, where A2-is the 3-0x0-glutarate ion and B is the aromatic amine, were responsible for the enhanced rates of decomposition. Kinetic and equilibrium measurements made it possible to compare the rate constants for decarboxylation of CuAB and CuA species. In fact the rate constants do not differ greatly, and the major enhancement of the rate arises from changes in the equilibria, and hence ...

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Section: Discussion Of Resultsmentioning

confidence: 56%

The Effect of Aromatic Amines on the Catalyzed Decarboxylation of 3-Oxo-glutaric Acid

Leong¹,

Lister²

1972

Can. J. Chem.

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“…To know the values of β 11 and β 12 , the study has been carried out at two constant concentrations of vitamin-PP i.e. 0.025 M and 0.050 M. The values of stability constant of complexes, given in Table 1, were obtained by using the Schaap and McMaster [13] method (Fig. 1).…”

Section: Polarographic Studiesmentioning

confidence: 99%

“…To compare the stability of binary and ternary complexes, the values of mixing constant log K m were calculated by the following equation [13]: …”

Section: Comparison Of Stability Of Binary and Ternary Complexesmentioning

confidence: 99%

Voltammetric Study and Thermodynamic Parameters of [Zn_L-Amino Acidate_Vitamin-PP] Complexes vis-à-vis Kinetics of Electrode Reaction

Khan¹,

Khanam²

2009

Port. Electrochim. Acta

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Voltammetric reduction of Zn (II) using L-lysine, L-ornithine, L-threonine, L-serine, Lphenylglycine, L-phenylalanine, L-glutamic acid, L-aspartic acid and vitamin-PP (nicotinamide, niacinamide) at pH = 7.30 ± 0.01, and µ = 1.0 M NaClO 4 was reported at 25 and 35 ºC. The nature of current voltage curves was quasireversible and diffusion controlled. Zn (II) formed 1:1:1, 1:1:2 and 1:2:1 complexes with these drugs as confirmed by Schaap and McMaster method. The sequence of stability constant of complexes L-lysine < L-ornithine < L-threonine < L-serine < L-phenylglycine < Lphenylalanine < L-glutamic acid < L-aspartic acid can be explained on the basis of size, basicity and steric hindrance of ligands. The thermodynamic parameters such as enthalpy (∆H), free energy (∆G) and entropy change (∆S) have also been reported. The kinetic parameters viz. transfer coefficient (α), degree of irreversibility (λ), diffusion coefficient (D) and standard rate constant (k) were calculated. The values of 'α' confirmed the symmetric nature of 'activated complex' between oxidants and reductants response to applied potential between dropping mercury electrode and solution interface.

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“…To compare the stability of binary and ternary complexes, the values of mixing constant log Km were calculated by the following equation [21]. …”

Section: Comparison Of Stability Of Binary and Ternary Complexesmentioning

confidence: 99%

Study of complexes of cadmium with some L-amino acids and vitamin-C by voltammetric technique

Khan

Khanam

2008

Eclet. Quím.

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Abstract:Voltammetric technique was used to study the binary and ternary complexes of cadmium with L-amino acids and vitamin-C (L-ascorbic acid) at pH =7.30 ± 0.01, µ = 1.0M KNO 3 at 25ºC and 35ºC. Cd (II) formed 1:1:1, 1:1:2 and 1:2:1 complexes with L-lysine, L-ornithine, L-threonine, L-serine, L-phenylglycine, L-phenylalanine, L-glutamic acid and L-aspartic acid used as primary ligands and L-ascorbic acid used as secondary ligand. The trend of stability constant of complexes was Llysine < L-ornithine < L-threonine < L-serine < L-phenylglycine < L-phenylalanine < L-glutamic acid < L-aspartic acid which can be explained on the basis of size, basicity and steric hindrance of ligands. The values of stability constant (log β) varied from 2.23 to11.33 confirm that these drugs i.e. L-amino acids or in combination with L-ascorbic acid or their complexes could be used against Cd (II) toxicity. The study has been carried out at 35ºC also to determine the thermodynamic parameters such as enthalpy change (∆H), Free energy change (∆G) and entropy change (∆S) respectively.

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A Polarographic Study of Mixed-ligand Complex Formation; Complexes of Copper and Cadmium with Oxalate Ion and Ethylenediamine

Cited by 185 publications

References 4 publications

The Effect of Aromatic Amines on the Catalyzed Decarboxylation of 3-Oxo-glutaric Acid

The Effect of Aromatic Amines on the Catalyzed Decarboxylation of 3-Oxo-glutaric Acid

Voltammetric Study and Thermodynamic Parameters of [Zn_L-Amino Acidate_Vitamin-PP] Complexes vis-à-vis Kinetics of Electrode Reaction

Study of complexes of cadmium with some L-amino acids and vitamin-C by voltammetric technique

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