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

• Main Author: Khan,Ahmad R.
• Publication Date: 2006
• Other Authors: Crans,Debbie C., Pauliukaite,Rasa, Norkus,Eugenijus
• Format: Article
• Language: eng
• Source: Journal of the Brazilian Chemical Society (Online)
• Download full: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532006000500012
• topic: vanadium(V); vanadium(IV); tartrate complexes; NMR and EPR spectroscopy; electrochemistry

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.