Stability constants of phosphineacetate complexes of divalent metals

1979 ◽  
Vol 44 (8) ◽  
pp. 2460-2464 ◽  
Author(s):  
Jana Podlahová
Keyword(s):  
Aqueous Solutions ◽  
General Formula ◽  
Stability Constants ◽  
Statistical Processing ◽  
The Other ◽  
Divalent Metals ◽  
Titration Curves ◽  
The Stability

Anions of the phosphineacetic acids of the general formula (C6H5)3-nP(CH2COOH)n (n = 1-3) form with the cations Mn2+, Co2+, Zn2+, Cd2+, and Pb2+ in aqueous solutions complexes with the ratio M : L = 1 : 1 and in some cases also 1 : 2. In addition, the ligand with n = 3 exhibits the formation of the protonized complexes MHL. The stability constants of the complexes were calculated by statistical processing of the pH-metric titration curves, and the ligands were found to act as the O-donors to Mn2+ and Zn2+, and as PO (n = 1) and POO (n = 2, 3) donors to the other cations.

scholarly journals Activity corrections for ionic equilibria in aqueous solutions

1980 ◽  
Vol 58 (12) ◽  
pp. 1253-1257 ◽  
Author(s):  
Mian S. Sun ◽  
Donald K. Harriss ◽  
Vincent R. Magnuson
Keyword(s):  
Ionic Strength ◽  
Stability Constant ◽  
Aqueous Solutions ◽  
General Formula ◽  
Stability Constants ◽  
Ionic Equilibria ◽  
Ion Activity ◽  
The Difference ◽  
Single Ion Activity ◽  
The Stability

Activity corrections for ionic equilibria in aqueous solutions at 25 °C and ionic strengths up to 0.5 have been investigated. An empirical formula for activity corrections was generated by statistically fitting stability constant data for approximately 540 complexes, for which both thermodynamic and concentration stability constants were known, to a modified Debye – Hückel relationship. The general formula is[Formula: see text]χ > 0, where Δ log K is the difference in the logarithms of the stability constants at infinite dilution and finite I (I ≤ 0.5), and χ is an even integer dependent only on the stoichiometry and charge of the ions involved. Activity correction formulae for ionic equilibria involving classes of ligands (amino acid, inorganic, amine, and organic acid) also were developed. The general formula predicts stability constant corrections within 0.1 log unit for 87 % of the data used at ionic strength 0.1 and 64 % of the data at ionic strength 0.5. In addition, single ion activity coefficients as a function of ionic strength, 0 < I ≤ 0.5, are presented.

The affinity of aldehydic compounds to complex formation. Nickel(II) and cobalt(II) complexes with 2-pyridinecarboxaldehyde

1977 ◽  
Vol 55 (14) ◽  
pp. 2613-2619 ◽  
Author(s):  
M. S. El-Ezaby ◽  
M. A. El-Dessouky ◽  
N. M. Shuaib
Keyword(s):  
Complex Formation ◽  
Aqueous Solutions ◽  
Stability Constants ◽  
Metal Ion ◽  
Experimental Conditions ◽  
Complex Species ◽  
Spectrophotometric Methods ◽  
Complex Equilibria ◽  
The Stability ◽  
Hydroxy Groups

The interactions of Ni(II) and Co(II) with 2-pyridinecarboxaldehyde have been investigated in aqueous solutions at μ = 0.10 M (KNO3) at 30 °C. The stability constants of different complex equilibria have been determined using potentiometric methods. Spectrophotometric methods were also used in the case of the nickel(II) – 2-pyridinecarboxaldehyde system. It was concluded that nickel(II) and cobalt(II), analogous to copper(II), enhance hyrdation of 2-pyridinecarboxaldehyde prior to deprotonation of one of the geminal hydroxy groups. Complex species of 1:1 as well as 1:2 metal ion to ligand composition exist under the experimental conditions used.

Determination of the stability constants for equilibriums involving copper(II) and fluoride ions in aqueous solutions

1974 ◽  
Vol 13 (6) ◽  
pp. 1434-1437 ◽  
Author(s):  
Sidney. Gifford ◽  
Wayne. Cherry ◽  
Joe. Jecmen ◽  
Mike. Readnour
Keyword(s):  
Aqueous Solutions ◽  
Stability Constants ◽  
Fluoride Ions ◽  
The Stability

Thermodynamic study of the complexation between Nd3+ and functionalized diacetamide ligands in solution

2016 ◽  
Vol 45 (30) ◽  
pp. 11968-11975 ◽  
Author(s):  
Phuong V. Dau ◽  
Zhicheng Zhang ◽  
Phuong D. Dau ◽  
John K. Gibson ◽  
Linfeng Rao
Keyword(s):  
Aqueous Solutions ◽  
Stability Constants ◽  
Thermodynamic Study ◽  
Amine Functionalized ◽  
The Stability ◽  
Diamide Ligands

Three amine-functionalized diamide ligands form tridentate complexes with Nd3+ in aqueous solutions. The stability constants of the complexes follow the order of the ligand basicity that can be tuned by different substitutional groups.

scholarly journals Stabilization of the Computation of Stability Constants and Species Distributions from Titration Curves

Computation ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 55
Author(s):  
Stephan Daniel Schwoebel ◽  
Dominik Höhlich ◽  
Thomas Mehner ◽  
Thomas Lampke
Keyword(s):  
Stability Constants ◽  
Thermodynamic Equilibrium ◽  
Measurement Errors ◽  
Alternative Model ◽  
Chemical Engineering ◽  
Species Distributions ◽  
Titration Curves ◽  
Deposited Metal ◽  
The Stability ◽  
Nickel Electrolyte

Thermodynamic equilibria and concentrations in thermodynamic equilibria are of major importance in chemistry, chemical engineering, physical chemistry, medicine etc. due to a vast spectrum of applications. E.g., concentrations in thermodynamic equilibria play a central role for the estimation of drug delivery, the estimation of produced mass of products of chemical reactions, the estimation of deposited metal during electro plating and many more. Species concentrations in thermodynamic equilibrium are determined by the system of reactions and to the reactions’ associated stability constants. In many applications the stability constants and the system of reactions need to be determined. The usual way to determine the stability constants is to evaluate titration curves. In this context, many numerical methods exist. One major task in this context is that the corresponding inverse problems tend to be unstable, i.e., the output is strongly affected by measurement errors, and can output negative stability constants or negative species concentrations. In this work an alternative model for the species distributions in thermodynamic equilibrium, based on the models used for HySS or Hyperquad, and titration curves is presented, which includes the positivity of species concentrations and stability constants intrinsically. Additionally, in this paper a stabilized numerical methodology is presented to treat the corresponding model guaranteeing the convergence of the algorithm. The numerical scheme is validated with clinical numerical examples and the model is validated with a Citric acid–Nickel electrolyte. This paper finds a stable, convergent and efficient methodology to compute stability constants from potentiometric titration curves.

scholarly journals STABILITY CONSTANTS OF L-ASPARAGINE AND L-LEUCINE COMPLEXES WITH SOME LANTHANIDE IN AQUEOUS SOLUTIONS AT 298.15 K

2017 ◽  
Vol 61 (1) ◽  
pp. 37
Author(s):  
Alexandr I. Lytkin ◽  
Natalya V. Chernyavskaya ◽  
Darya K. Smirnova
Keyword(s):  
Amino Acids ◽  
Aqueous Solutions ◽  
Stability Constants ◽  
Quantitative Estimation ◽  
A Priori ◽  
Complex Compounds ◽  
Complexing Agent ◽  
Stability Of Complexes ◽  
Biological Substrates ◽  
The Stability

Lanthanides have a high affinity toward ligands containing donor oxygen atoms, especially amino acids and complexons. The study of the processes of complexation of amino acids with f-element cations provides valuable information for solving problems of supramolecular chemistry, molecular recognition and chiral sensitivity of biological substrates. As a rule, f-elements are not components of biopolymers, but they are spectral label probes, which are important in the bioinorganic chemistry of metals. Quantitative estimation of the stability of complexes is necessary, first of all, to search for an internal connection between the constants themselves and then to find correlations between the stability of complexes and the properties of the complexing agent, the ligand, and the system as a whole. Such correlation dependencies make it possible to calculate a priori, or at least estimate the stability constants of new complexes, and also to better understand the influence of the nature of the chemical bond and the properties of the system as a whole on the formation and stability of complex compounds. In the present work, the complexation of neodymium, lanthanum with L-asparaginat ion and samarium, cerium with L-leucinat ion at 298.15 K and ionic strength values of 0.5 mol/l was studied by potentiometric titration and the stability constants of the complexes formed were determined. The values of the stability constants found allow us to perform rigorous thermodynamic calculations of the equilibria of these amino acids in salt solutions. The data obtained, in particular, can be used to reliably interpret the results of calorimetric studies of the complexation of lanthanides with the participation of the studied amino acids.Forcitation:Lytkin A.I., Chernyavskaya N.V., Smirnova D.K. Stability constants of L-asparagine and L-leucine complexes with some lanthanide in aqueous solutions at 298.15 K. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 1. P. 37-41

pH dependence of the stability constants of copper(I) complexes with fumaric and maleic acids in aqueous solutions

1997 ◽  
Vol 261 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Nadav Navon ◽  
Alexandra Masarwa ◽  
Haim Cohen ◽  
Dan Meyerstein
Keyword(s):  
Aqueous Solutions ◽  
Stability Constants ◽  
Ph Dependence ◽  
The Stability
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