Polarographic study of the mixed complexes of Cd(II) with oxalate and malonate ions

1988 ◽  
Vol 53 (3) ◽  
pp. 506-514 ◽  
Author(s):  
Cesar Rodríguez-Placeres ◽  
Graciliano Ruiz-Cabrera ◽  
Ana Alloza ◽  
Agustin Arévalo
Keyword(s):  
Ionic Strength ◽  
Aqueous Medium ◽  
Stability Constants ◽  
Polarographic Study ◽  
Mixed Complexes ◽  
Overall Stability

The coordinated mixed Cd(II)-oxalate-malonate system has been polarographically studied in aqueous medium. The ionic strength has been maintained constant at μ = 1.0 mol l-1 by using NaClO4. The overall stability constants, determined by using the Schaap and McMasters method, for the coordinated species [Cd(ox)(mal)]2-, [Cd(ox)(mal)2]4- and [Cd(ox)2(mal)]4- are respectively β11 = 1.3 . 104 l2 mol-2, β12 = 5.0 . 104 l3 mol-3 and β21 = 8.7 . 104 l3 mol-3. The various coordination equilibria are discussed on the basis of statistical aspects.

scholarly journals Studies of Binary Complexes of Tripodal Ligandcis,cis-1,3,5-tris(methylamino)cyclohexane with Cr(III) and Fe(III)

2005 ◽  
Vol 2 (1) ◽  
pp. 52-57
Author(s):  
S. Esakki Muthu ◽  
Suban K. Sahoo ◽  
Minati Baral ◽  
B. K. Kanungo
Keyword(s):  
Ionic Strength ◽  
Aqueous Medium ◽  
Molecular Mechanics ◽  
Stability Constants ◽  
Potentiometric Method ◽  
Molecular Mechanics Calculations ◽  
Tripodal Ligand ◽  
Binary Complexes ◽  
Overall Stability ◽  
Mode Of Coordination

The formation of binary complexes of Cr(III) and Fe(III) with a tripodal ligandcis,cis-1,3,5-tris(methylamino)cyclohexane (tmach) (L) has been investigated in solution. The overall stability constants oftmachwith Cr(III) and Fe(III) were determined by potentiometric method at an ionic strength of 0.1 M NaClO4at 25±1°C in aqueous medium. The formation of species like MLH25+, MLH4+, ML3+, ML(OH)2+and ML(OH)3were observed. Fe(III) was found to form more stable complexes than Cr(III). Molecular mechanics calculations were performed to explain the mode of coordination in solution.

Stabilities of Vanadyl Complexes with Methionine, Phenylalanine, and Threonine

1974 ◽  
Vol 29 (7-8) ◽  
pp. 336-338
Author(s):  
B.S. Sekhon ◽  
S.L. Chopra
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Stability Constants ◽  
Thermodynamic Stability ◽  
Chloride Solution ◽  
Formation Constants ◽  
Potassium Chloride Solution ◽  
Vanadyl Complexes ◽  
Overall Stability ◽  
Stepwise Formation

Abstract Stepwise formation constants corresponding to 1:1 vanadyl complexes with methionine, phenylalanine and threonine have been determined at 25 °C, and at various ionic concentrations, viz. 0.01, 0.1 and 0.3 ᴍ , maintained by the addition of potassium chloride solution. Thermodynamic stability constants have been obtained by extrapolation of log K values to zero ionic strength. Logarithms of the overall stability constants (log K (u = 0)) are 7.72 for methionine, 7.70 for phenyl­alanine and 7.44 for threonine complexes. The corresponding free energy changes (⊿G0) are - 10.53, - 10.51, - 10.15 kcal-mol-1 respectively.

Interligand interaction in ternary complexes of Zn(II) and Cd(II) with dipeptides and aminoacids

1994 ◽  
Vol 72 (4) ◽  
pp. 1107-1110 ◽  
Author(s):  
Alexander Varghese Vaidyan ◽  
Pabitra K. Bhattacharya
Keyword(s):  
Ionic Strength ◽  
Aqueous Medium ◽  
Computer System ◽  
Stability Constants ◽  
Ternary Complexes ◽  
Binary And Ternary Complexes ◽  
The Stability ◽  
Interligand Interaction

The stability constants of binary and ternary complexes [MA], [Ma2], and [MAL] (where M = Zn(II) or Cd(II); A = glycylglycine, glycyl L-alanine, glycyl L-leucine; L = α-alanine phenylalanine, tyrosine, tryptophan, or L-histidine) in aqueous medium have been determined potentometrically at 25 °C and an ionic strength of 0.2 M NaClO4 (0.2 mol dm−3) using a computer system. It is observed that Δ log K of MAL complexes has low negative or positive values. Probable reasons have been discussed.

Complexation binaire et ternaire des ions Cu(II), Hg(II) et Pt(II) par la D-valine et une série d'homologues de l'uracile

1989 ◽  
Vol 67 (6) ◽  
pp. 973-982 ◽  
Author(s):  
Raoul M'boungou ◽  
Michelle Petit-Ramel ◽  
Germaine Thomas-David ◽  
Gérard Perichet ◽  
Bernard Pouyet
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Orotic Acid ◽  
Protonation Constants ◽  
Second Step ◽  
Simple Method ◽  
Mixed Complexes ◽  
The Stability

The protonation constants of uracil (UR), cytosine (CY), and D-valine (VA) have been calculated at 25 °C and at ionic strength μ = 0.1 (NaNO3). In a first step the stability constants of their Cu(II), Hg(II) and Pt(II) simple complexes were determined. In a second step the mixed complexation of several uracil homologues as thymine, thymidine, orotic acid and cytosine was also investigated under the same conditions by protometric methods. Concerning the mixed complexes, a new simple method of estimating their stability constants has been developed and verified. Keywords: Cu(II), Hg(II), Pt(II) coordination, ternary coordination, uracil homologues, D-valine, protometric methods.

Study of the Mixed Coordinated Systems Cu(II)-Valinate Ion-Glycinate Ion and Cu(II)-Valinate Ion-Leucinate Ion

1992 ◽  
Vol 57 (7) ◽  
pp. 1405-1409 ◽  
Author(s):  
María Teresa Sanz Alaejos ◽  
Jesús César Rodríguez Placeres ◽  
Francisco J. García Montelongo
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Sodium Perchlorate ◽  
Ternary Systems ◽  
Mixed Ligand ◽  
Mixed Complexes ◽  
Glycinate Ion

The mixed ligand ternary systems Cu(II)-valinate ion-glycinate ion and Cu(II)-valinate ion-leucinate ion have been studied polarographically at 25 ± 0.1 °C and at ionic strength 1.0 mol l-1, adjusted with sodium perchlorate. The formation of the mixed complexes [Cu(Val-)(Gly-)] and [Cu(Val-)(Leu-)] have been verified, with stability constants β11 = (4.6 ± 0.2).1015 and β11 = (7.2 ± 0.3).1015, respectively.

Some Novel Amino Acid-Schiff Bases and their Complexes Synthesis, Characterization, Solid State Conductivity Behaviors and Potentiometric Studies

2004 ◽  
Vol 59 (6) ◽  
pp. 692-698 ◽  
Author(s):  
Nurşen Sarı ◽  
Perihan Gürkan
Keyword(s):  
Amino Acid ◽  
Ionic Strength ◽  
Solid State ◽  
Aqueous Medium ◽  
Spectral Data ◽  
Schiff Bases ◽  
Stability Constants ◽  
Room Temperature ◽  
Condensation Reaction ◽  
Potentiometric Studies

Three new Schiff bases derived from the condensation reaction of thiophene-2-carbaldehyde and DL-alanine, DL-valine and DL-phenylalanine have been synthesized and their Co(II), Ni(II) and Cu(II) complexes have been prepared. The Schiff bases and the complexes have been characterized by their analytical and spectral data. The protonation constants of the Schiff bases and stability constants of the complexes have been determined potentiometrically in aqueous medium at 25 °C and 0.1 M KCl ionic strength. Solid state conductivities of the synthesized substances were using the four-probe technique on a compressed pellet at room temperature.

Extraction of hafnium(IV) with organophosphorus reagents from solutions of mineral acids mixtures

1979 ◽  
Vol 44 (12) ◽  
pp. 3656-3664
Author(s):  
Oldřich Navrátil ◽  
Jiří Smola ◽  
Rostislav Kolouch
Keyword(s):  
Ionic Strength ◽  
Aqueous Phase ◽  
Organic Phase ◽  
Perchloric Acid ◽  
Synergic Effect ◽  
Salting Out ◽  
Initial Concentration ◽  
Mixed Complexes ◽  
Synergic Extraction ◽  
Mineral Acids

Extraction of hafnium(IV) was studied from solutions of mixtures of perchloric and nitric acids and of perchloric and hydrochloric acids for constant ionic strength, I = 2, 4, 6, or 8, and for cHf 4 . 10-4 mol l-1. The organic phase was constituted by solutions of some acidic or neutral organophosphorus reagents or of 2-thenoyltrifluoroacetone, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, or N-benzoyl-N-phenylhydroxylamine in benzene, chloroform, or n-octane. A pronounced synergic extraction of hafnium proceeds only on applying organophosphorus reagents from an aqueous phase whose acidity is not lower than 3M-(HClO4 + HNO3) or 5M-(HClO4 + HCl). The synergic effect was not affected markedly by a variation of the initial concentration of hafnium in the range 1 . 10-8 -4 .10-4 mol l-1, it lowered with increasing initial concentration of the organophosphorus reagent and decreasing concentration of the H+ ions. It is suggested that the hafnium passes into the organic phase in the form of mixed complexes, the salting-out effect of perchloric acid playing an appreciable part.

EUROPIUM OXALATE ION ASSOCIATION IN WATER

1966 ◽  
Vol 44 (24) ◽  
pp. 3057-3062 ◽  
Author(s):  
P. G. Manning
Keyword(s):  
Acetic Acid ◽  
Ionic Strength ◽  
Stability Constant ◽  
Stability Constants ◽  
Aqueous Phase ◽  
Sodium Acetate ◽  
Ion Association ◽  
Sodium Oxalate ◽  
Aqueous Sodium ◽  
Oxalate Ion

The partitioning of radiotracer 152/151Eu between aqueous sodium oxalate (Na2L) solutions and toluene solutions of thenoyltrifluoroacetone (HTTA) has been studied as a function of the oxalate concentration. The pH of the aqueous phase was controlled by means of sodium acetate – acetic acid mixtures and the ionic strength (I) by NaCl or NaClO4.At low ionic strengths (~0.05) and [L] ~10−4 M EuL+ formed, but at I = 0.95 and [L] ~10−3 M EuL2− also formed. Stability constants for the 1:1 and 1:2 (metal:ligand) complexes are reported.The magnitudes of the stepwise stability constant ratios are discussed.

scholarly journals Stability Studies of Transition Metal Chelates of 5-Bromosalicylidene-4-methoxyaniline andSalicylidene-2,3-dimethylaniline as Ligands

2011 ◽  
Vol 8 (4) ◽  
pp. 1911-1915
Author(s):  
N. G. Nadkarni ◽  
K. V. Mangaonkar
Keyword(s):  
Ionic Strength ◽  
Transition Metal ◽  
Stability Constants ◽  
Metal Chelates ◽  
Ternary Complexes ◽  
Water Medium ◽  
Stability Studies ◽  
Binary And Ternary Complexes ◽  
Transition Metal Chelates ◽  
The Stability

Binary and ternary complexes of the type M-Y and M-X-Y [M = Mn(II), Ni(II), Cu(II) and Zn(II); X = 5-bromosalicylidene-4-methoxyaniline and Y = salicylidene-2,3-dimethylaniline] have been examined pH-metrically at 27±0.5°C and at constant ionic strength, μ = 0.1 M (KCl) in 75 : 25(v/v) 1,4-dioxne-water medium. The stability constants for binary (M-Y) and ternary (M-X-Y) systems were calculated.

Sign in / Sign up

Export Citation Format

Share Document