Study on the Complexation of Molybdenum(VI) with Iminodiacetic Acid and Ethylenediamine‐N,N′‐diacetic Acid by Specific Ion Interaction and Debye‐Hückel Theories

Abstract

Complexation of two ligands, iminodiacetic acid and ethylenediamine-N,N'-diacetic acid, with molybdenum(VI) was studied in aqueous solutions. Molybdenum(VI) forms a mononuclear complex with the aforementioned ligands of the type MoO 3 L 2-. All measurements have been carried out at 25 ℃ and different ionic strengths ranging from 0.1 to 1.0 mol•L -1 of NaClO 4 , with the pH justified to 6.0. Equilibrium concentration products and stoichiometry of the complexes have been determined from a combination of potentiometric and UV spectroscopic measurements.Comparison of the ionic strength effect on these complex formation reactions has been made using a Debye-Hückel type equation and Bronsted-Guggenheim-Scatchard specific ion interaction theory (SIT). Debye-Hückel theory predicted the first order effects on simple electrolyte solutions. Interactions between the reacting species and the ionic medium were taken into account in the SIT model. All of the calculations have been done by the computer program Excel 2000.

Complexation of Molybdenum(VI) with Ethylenediaminediacetic Acid in Different Water + Methanol Solutions

“…Stability constants have been calculated at different mole fractions of methanol by combination of the following equations according to our previous works for aqueous solutions [33][34][35][36][37][38][39][40] …”

Determination of Solvatochromic Regression Coefficients for the Molybdenum(VI) Complex with Ethylenediamine‐N,N′‐diacetic Acid by Using Kamlet‐Abboud‐Taft Equation

“…9 Continuous variations data and stability constants for the Mo(VI)＋EDDA system at pH ＝ 6.00, I ＝ 0.1 mol•L -1 and different wavelengths and aqueous solutions of methanol have been reported previously. 7 The molar absorptivity values of the complex, ε 1 , were calculated at low mole fraction of the metal, where essentially all the metal ions were in the form of a complex.…”

“…7 The molar absorptivity values of the complex, ε 1 , were calculated at low mole fraction of the metal, where essentially all the metal ions were in the form of a complex. 9,[20][21][22][23] [C] is the concentration of the complex. 9,[20][21][22][23] Solvent effects on the complexation of molybdenum(VI) with EDDA by using Kamlet-Abboud-Taft equation Solvent polarity can be estimated empirically by using actual chemical or physical reference processes.…”

“…9 In all experiments double-distilled water with a specific conductance equal to (1.3± 0.1) µS•cm -1 has been used. 9 …”

Complexation of molybdenum(VI) with methyliminodiacetic acid in different water + methanol solutions

“…Investigation of the solvent effect in complex formation reactions is the subject of ongoing research [1][2][3][4] aimed at comparing the new results with previous data in aqueous solutions [5][6][7][8][9][10] and understanding the contribution of the solvent in various interactions in alcoholic and ionic liquid solutions. The study of the solvent effect could be considered as a kind of simulation for the cases where the solvent polarity decreases.…”