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RESEARCH PRODUCT
Compounds of tungsten(VI) with citric acid: A spectrophotometric, polarimetric and hydrogen-1, carbon-13 N.M.R. study of the formation and interconversion equilibria in aqueous solution
Elisa LlopisAntonio CervillaJose Antonio Ramirezsubject
Aqueous solutionInorganic chemistryMetals and Alloyschemistry.chemical_elementTungstenOxygenCatalysisInorganic Chemistrychemistry.chemical_compoundchemistryStability constants of complexesMaterials ChemistryMoleculeStoichiometryOrganometallic chemistrydescription
Tungsten(VI)-citrate complexes, which occur in aqueous solution, were studied by polarimetric and absorbance measurements. The pH of the medium is the principal variable controlling complex formation and interconversion equilibria. At high pH (>6), the stable complexes are monomers with 1∶2 and 1∶1 stoichiometry, depending on the tungsten(VI)-citrate ratio, while at lower pH two different dinuclear complexes are formed. The intervals of existence of these species with the pH, the number of equivalents of acid necessary for their formation, as well as the conditional stability constant, have also been calculated. The structure of these compounds have been investigated by1H and13C-n.m.r. spectroscopy. The n.m.r. results indicate the existence in all these species of strong, covalent metal-toligand oxygen bondingvia the carboxylic oxygen atom and the adjacent hydroxylic oxygen.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1986-05-01 | Transition Metal Chemistry |