Study on the Chelate Formation and the Ion-association of Anionic Chelate of Molybdenum(VI) with 3,5-Dinitrocatechol and Monotetrazolium Cation

Kirila Stojnova,Kristina Bozhinova,Vidka Divarova,Vanya Lekova,Petya Racheva

doi:10.17344/acsi.2017.3860

Abstract

The equilibria of the chelate formation and ion-association in the liquid-liquid extraction system Mo(VI)‒3,5-DNC‒INT‒H2O‒CHCl3 were studied by spectrophotometry. The optimum conditions for the chelate formation and extraction of the ion-associated complex formed between the anionic chelate of Mo(VI)‒3,5-dinitrocatechol (3,5-DNC) and the cation of 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride (INT) were established. The validity of Beer's law was checked and some analytical characteristics were calculated. The effect of various co-existing ions and reagents on the process of complex formation was investigated. The molar ratio of the components in the ternary ion-associated complex Mo(VI)-3,5-DNC-INT was determined by independent methods. The association process in aqueous phase and the extraction equilibria were investigated and quantitatively characterized. The following key constants of the processes were calculated: association constant, distribution constant, extraction constant and recovery factor. Based on this, a reaction scheme, a general formula and a structure of the complex were suggested.

Highlights

The molybdenum and its compounds are widely used in various important areas of technology, science, and medicine
The absorption spectrum of the extract of the ion-associated complex formed between the anionic chelate of Mo(VI)‒3,5-DNC and the cation of monotetrazolium salt
The equilibria of the chelate formation and extraction of the ion-associated complex formed between the anionic chelate of Mo(IV)‒3,5-dinitrocatechol (3,5-DNC) and the cation of 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl2H-tetrazolium chloride (INT) was studied by spectrophotometry

Summary

Introduction

The molybdenum and its compounds are widely used in various important areas of technology, science, and medicine. Molybdenum is present in all living plant and animal matter in micro-trace quantities and it is essential from a biochemical point of view. It stimulates the synthesis of nucleic acids and proteins. The molybdenum has a rich chemistry, it occurs in various oxidation states, coordination numbers and geometries.[1,5,6] Molybdenum(VI) forms complexes with various natural organic ligands, such as polyphenols and their functional derivatives, polyhydroxycarboxylic acids, aminopolycarboxylic acids, hydroxamic acids, amines (primary, secondary and tertiaty), 8-hydroxyquinoline and its derivatives, aldehyde hydrazones, oximes, β-diketones, fluorones, hydroxyazodyes, biomolecules (chitosan, chitin, D-glucosamine, L-alanine, L-phenylalanine).[7,8,9,10,11,12,13,14,15,16,17,18,19,20] Molybdenum(VI) gives colored chelates with aromatic compounds, containing two or more hydroxyl groups in ortho position relative to each other. The colored anionic chelates of molybdenum(VI) form ion-associated complexes

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