A SPECTROPHOTOMETRIC REEXAMINATION OF THE SPECTRA AND STABILITIES OF THE IRON (III) – TIRON COMPLEXES

1964 ◽  
Vol 42 (8) ◽  
pp. 1917-1927 ◽  
Author(s):  
W. A. E. McBryde
Keyword(s):  
Aqueous Solutions ◽  
Stability Constants ◽  
Equilibrium Constants ◽  
Sodium Perchlorate ◽  
Potassium Nitrate ◽  
Low Ph ◽  
Exact Nature ◽  
Simple Complex ◽  
Acidity Constants ◽  
The Stability

Variations in the spectra of the aqueous solutions of the iron (III) – sodium catechol disulphonate (Tiron) complexes may be interpreted in relation to pH of the solutions to show which complexes are present at any chosen pH. With this knowledge it is possible in this system to evaluate equilibrium constants for the formation of each complex in turn. Combining these with separately determined acidity constants for Tiron, the stability constants of the complexes may be calculated. These have been determined for background solutions of potassium nitrate or sodium perchlorate each at three different concentrations, and for three different ratios of reagent to metal. Averages of a number of determinations made under these conditions are given in Table III of the paper. The constant K1 in perchlorate media shows an unmistakable dependence suggestive of the existence of a protonated species at low pH as well as the simple complex ML. However, there is some ambiguity in the interpretation of the results so that the exact nature of the protonated complex cannot be decided.

Stability constants of three iron(III) salicylates

1970 ◽  
Vol 48 (16) ◽  
pp. 2574-2586 ◽  
Author(s):  
W. A. E. McBryde ◽  
Janet L. Rohr ◽  
J. S. Penciner ◽  
J. A. Page
Keyword(s):  
Stability Constants ◽  
Equilibrium Constants ◽  
Background Electrolyte ◽  
Aminosalicylic Acid ◽  
Sulfosalicylic Acid ◽  
Spectrophotometric Measurement ◽  
Acidity Constants ◽  
Extinction Coefficients ◽  
The Stability ◽  
Improved Methods

Stability constants of the iron(III) complexes of salicylic acid, sulfosalicylic acid, and 4-aminosalicylic acid, together with several of the acidity constants of these, have been determined at 25 °C and in solutions with 0.5 M background electrolyte. For the spectrophotometric measurement of the stability constants improved methods for determining the extinction coefficients of the first and second complexes are described. Protonated species appear only with the aminosalicylate complexes, and the site of this protonation is discussed. Previous values of these equilibrium constants have been collected and critically assessed.

Constraints on the determination of stability constants for metal complexes. II. The iron(III) phenolates

1968 ◽  
Vol 46 (14) ◽  
pp. 2385-2392 ◽  
Author(s):  
W. A. E. McBryde
Keyword(s):  
Metal Complexes ◽  
Stability Constants ◽  
Equilibrium Constants ◽  
Low Ph ◽  
Experimental Results ◽  
Good Precision ◽  
Acidity Constants ◽  
Extinction Coefficients ◽  
Molar Extinction Coefficients

Stability constants have been measured spectrophotometrically for the 1:1 complexes of iron(III) with phenol and five derivatives in background solutions having two different compositions, 0.027 M NaClO4 and 0 5 M KNO3 Conditional acidity constants for these phenols in the second of these media were also determined The experimental results were treated in two different ways to obtain values of the equilibrium constants and the molar extinction coefficients of the complexes It is apparent that the equilibrium in these cases must be studied under conditions, such as low pH and low concentration of iron, which militate against good precision in the results

Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

1985 ◽  
Vol 50 (3) ◽  
pp. 581-599 ◽  
Author(s):  
Petr Vaňura ◽  
Emanuel Makrlík
Keyword(s):  
Stability Constants ◽  
Organic Phase ◽  
Equilibrium Constants ◽  
Minor Role ◽  
Nitrobenzene Solution ◽  
Ligand Structure ◽  
Stability Constants Of Complexes ◽  
Separation Factors ◽  
The Stability ◽  
A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

Some phase relationships between basic bismuth chlorides in aqueous solutions at 25 °C

1987 ◽  
Vol 65 (12) ◽  
pp. 2824-2829 ◽  
Author(s):  
Peter Taylor ◽  
Vincent J. Lopata
Keyword(s):  
Aqueous Solutions ◽  
Equilibrium Constants ◽  
Natural Occurrence ◽  
Chloride Solutions ◽  
Gibbs Energies ◽  
Activity Ratios ◽  
Aqueous Chloride ◽  
The Stability ◽  
Experimental Values ◽  
Phase Relationships

Observations are reported on the interconversion of solid α-Bi2O3, Bi12O17Cl2, BiOCl, and a daubréeite-like phase tentatively identified as Bi2O2(OH)Cl, in aqueous chloride solutions at 25 °C. Equilibrium constants, K, for these interconversions are expressed as anion activity ratios, {Cl−}/{OH−}. Experimental values of K for equilibrium between Bi2O3 and each of the chlorides are 100.56 ± 0.20 for Bi12O17Cl2, 101.5 ± 0.4 for Bi2O2(OH)Cl, and 103.13 ± 0.04 for BiOCl; the fatter two represent metastable equilibria. These equilibrium constants yielded the following estimates of Gibbs energies of formation: Bi12O17Cl2, −3141 ± 6 kJ mol−1;"Bi2O2(OH)Cl", −696 ± 4 kJ mol−1; BiOCl, −321.5 ± 1.3 kJ mol−1. Phase relationships among these solids are discussed, with reference to natural occurrence, other bismuth oxychlorides, and the stability of other basic salts of bismuth.

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.

scholarly journals Thermodynamic and Spectroscopic Studies of the Complexes Formed in Tartaric Acid and Lanthanide(III) Ions Binary Systems

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1121 ◽  
Author(s):  
Michal Zabiszak ◽  
Martyna Nowak ◽  
Zbigniew Hnatejko ◽  
Jakub Grajewski ◽  
Kazuma Ogawa ◽  
...  
Keyword(s):  
Tartaric Acid ◽  
Stability Constants ◽  
Binary Systems ◽  
Equilibrium Constants ◽  
Spectroscopic Studies ◽  
Luminescence Spectroscopy ◽  
Binary Complexes ◽  
Overall Stability ◽  
The Stability

Binary complexes of tartaric acid with lanthanide(III) ions were investigated. The studies have been performed in aqueous solution using the potentiometric method with computer analysis of the data for detection of the complexes set, determination of the stability constants of these compounds. The mode of the coordination of complexes found was determined using spectroscopy, which shows: Infrared, circular dichroism, ultraviolet, visible as well as luminescence spectroscopy. The overall stability constants of the complexes as well as the equilibrium constants of the reaction were determined. Analysis of the equilibrium constants of the reactions and spectroscopic data allowed the effectiveness of the carboxyl groups in the process of complex formation.

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
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