Spectrometric and electrochemical investigation of vanadium(V) and vanadium(IV) tartrate complexes in solution

Spectroscopic and electrochemical studies were carried out to characterize the vanadium(IV) and (V) complexes that form in solution and their interconversions. 51V NMR spectroscopy coupled with ¹H NMR, 13C NMR and EPR spectroscopy were used to characterize the vanadium(V)-tartrate complexes that form in the vanadium-tartrate system. The major complex that forms over most of the pH range is a 1:1 complex. In addition a minor 1:2 complex forms. The 1:2 complex formed from enantiomerically pure tartaric acid was less stable than complex formed from racemic tartaric acid. These complexes are different than the 2:2 complex that is the major contributor in the vanadium(IV)-tartrate system. The polarographic and cyclic voltammetic investigations of the electrochemical behavior of V(V) in the presence of tartrate demonstrated a complex formation. The diffusion coefficient values of free vanadium ions and vanadium-tartrate complexes were determined. The minimum average values for the diffusion coefficient for the vanadium(IV)-tartrate 2:2 complexes were determined to range from 3 <FONT FACE=Symbol>´</FONT> 10-6 cm² s-1 to 17 <FONT FACE=Symbol>´</FONT> 10-6 cm² s-1 depending on pH.

Bibliographic Details

Main Authors:	Khan,Ahmad R., Crans,Debbie C., Pauliukaite,Rasa, Norkus,Eugenijus
Format:	Digital revista
Language:	English
Published:	Sociedade Brasileira de Química 2006
Online Access:	http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532006000500012
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