Octahedral cobalt(III) complexes in dipolar aprotic solvents. III. A new spectrophotometric method for the determination of ion association constants

A spectrophotometric method for the evaluation of ion association constants has been developed. This method involves the preparation of solutions containing only the compound under consideration. A function relating the association constants to the concentration of compound and extinction coefficients has been derived. The association constants are best determined by an iterative method using a computer. The association constant for the cis-diohlorobisethylenediaminecobalt(111) cation, cis-[Co en2 Cl2]+, and chloride ion in NN-dimethylformamide (DMF) at 30� has been calculated by this new method and is compared with that of another established procedure. The association constant has also been determined for the association of cis-[Co en2 Cl2]+ and iodide in DMF at 30�.

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Octahedral cobalt(III) complexes in dipolar aprotic solvents. II. Association between cis- and trans-dichlorobisethylenediamine cobalt(III) cations,[Co en2 Cl2]+, and chloride and bromide ions in the solvents NN-dimethylformamide, dimethyl sulphoxide, and LVN-dimethylacetamide

Australian Journal of Chemistry ◽

10.1071/ch9660043 ◽

1966 ◽

Vol 19 (1) ◽

pp. 43 ◽

Cited By ~ 15

Author(s):

WA Millen ◽

DW Watts

Keyword(s):

Spectrophotometric Method ◽

Ion Pairs ◽

Ion Association ◽

Ion Pair ◽

Association Constants ◽

Dimethyl Sulphoxide ◽

Aprotic Solvents ◽

Ion Association Constants ◽

Cis And Trans ◽

Dipolar Aprotic Solvents

Ion association constants at 30� have been determined for the cis-[Co en, Cl2]+Cl- ion pair in NN-dimethylformamide (DMF), NN-dimethylacetamide (DMA), and at 20.0�, 25.0�, and 30.0� in dimethyl sulphoxide (DMSO), by a spectrophotometric method. Association constants for the cis-[Co en2 Cl2]+Br- and the trans- [Co en2 Cl2]+Cl- ion pairs have also been determined in DMF at 30�.

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Octahedral cobalt(III) complexes in dipolar aprotic solvents. VI. Spectrophotometric determination of ion association of halide ions with cis-chlorodimethylformamidebisethylenediaminecobalt(III) ion and cis-chlorobromobisethylenediaminecobalt(III)ion in anhydrous NN-dimethylformamide

Australian Journal of Chemistry ◽

10.1071/ch9660969 ◽

1966 ◽

Vol 19 (6) ◽

pp. 969 ◽

Cited By ~ 6

Author(s):

IR Lantzke ◽

DW Watts

Keyword(s):

Ion Association ◽

Cobalt Complexes ◽

Complex Salt ◽

Ion Pair ◽

Association Constants ◽

Halide Ions ◽

Kcal Mole ◽

Ion Association Constants ◽

Dipolar Aprotic Solvents

Using a spectrophotometric technique the ion association constants for three systems of octahedral cobalt complexes and halide ions have been determined at three temperatures in NN-dimethylformamide. The values of K, ΔH�, and ΔS� for each system have been calculated. At 30� they are as follows: cis-[CoCl(DMF) en2]2+ + Cl- ↔ ion pair K=1.51�0.03 x 104 1.mole-1(ΔH0= 0.93 � 0.02 kcal mole-1,ΔS�= 22.l+0.4 e.u) cis-[CoCl(DMF) en2]2++2Cl- ↔ ion triplet K= 1.21�0.05 X 106 1.2 mole-2(ΔH�=-3.8�0.lkcal mole-1, ΔS�=15.41� 0.5 e.u) cis-[CoCl(DMF) en2]2++Br- ↔ ion pair K= 9.20�0.18 X 103 1.1 mole-1(ΔH�=-7.2�0.lkcal mole-1, ΔS�=42� 1.0 e.u) cis-[CoBrCl en2]+ + Br- ↔ ion pair K = 690�l41. mole-1 (ΔH� = 1.27�0.03 kcal mole-1, ΔS�= 8.8�0.2 e.u.) The dependence of the measured K, the association constant, on the wavelength of measurement, small amounts of water in the solvent, and the anion of the complex salt, has also been investigated.

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Investigation of the extraction equilibrium of ion-association complexes of molybdenum (VI) with some polyphenols and thiazolyl blue. extraction-spectrophotometric determination of molybdenum

Open Chemistry ◽

10.2478/bf02475202 ◽

2005 ◽

Vol 3 (4) ◽

pp. 747-755 ◽

Cited By ~ 1

Author(s):

Atanas Dimitrov ◽

Vania Lekova ◽

Kiril Gavazov ◽

Boyan Boyanov

Keyword(s):

Organic Solvent ◽

Aqueous Medium ◽

Spectrophotometric Method ◽

Ion Association ◽

Extraction Process ◽

Association Constants ◽

Optimum Conditions ◽

Extraction Equilibrium ◽

Simple Extraction

AbstractThe extraction process of ternary ion-association complexes of molybdenum (VI) with some polyphenols (4-nitrocatechol, 2,3-dihydroxy naphthalene) and thiazolyl blue has been investigated by using an extraction-spectrophotometric method. The optimum conditions for their quantitative preparation in aqueous medium and subsequent extraction into an organic solvent have been found. The extraction, distribution and association constants, and the recovery factors have been calculated. The composition of the complexes has been determined. A precise, sensitive and simple extraction-spectrophotometric method for determination of molybdenum in products from ferrous metallurgy has been developed.

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