Ultraviolet–visible spectrophotometric determination of ion-association constants for alkylpyridinium iodides. N-ethyl-4-cyanopyridinium iodide in mixed solvents containing ethanol

1985 ◽  
Vol 81 (4) ◽  
pp. 961 ◽  
Author(s):  
Mohan Pal ◽  
Sanjib Bagchi
Keyword(s):  
Spectrophotometric Determination ◽  
Mixed Solvents ◽  
Ion Association ◽  
Association Constants ◽  
Ion Association Constants

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

1966 ◽  
Vol 19 (6) ◽  
pp. 969 ◽  
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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