Multicomponent Polyanions, 49: A Potentiometric and (31P, 51V) NMR Study of the Aqueous Molybdovanadophosphate System
2000 (English)In: European Journal of Inorganic Chemistry, Vol. 7, 1509-21 p.Article in journal (Refereed) Published
The equilibrium speciation of the quaternary system H+/MoO42-/HVO42-/HPO42- in aqueous 0.600 M Na(Cl) at 25 °C and 90 °C was studied by pH potentiometry and 31P (202.5 MHz) and 51V (131.6 MHz) NMR spectrometry. The study focused on solutions containing the oxoanion components in the ratios (Mo + V)/P = 12:1 and Mo/V 3.8, in the pH range 0-5, wherein Keggin anions of the formula [HzMo12-xVxPO40](3+x-z)- with x = 1-3 are the predominant species. Formation constants (log ) and pKa values for Keggin anions with x = 1-3 were determined from 31P and 51V resonance chemical shift data, 31P resonance intensity data, and pH potentiometric data with the multidata least squares calculation program LAKE. The [Mo11VPO40]4- anion does not protonate, [Mo10V2PO40]5- anions can be monoprotonated, and [Mo9V3PO40]6- anions can be triprotonated. The six most intense 31P NMR resonances of [HzMo9V3PO40](6 - z)- could be followed over the pH range studied. It was also possible to assign some 31P resonances to a specific isomer of [Mo9V3PO40]6-.
Place, publisher, year, edition, pages
2000. Vol. 7, 1509-21 p.
Polyoxometalates, Phosphorus, Vanadium, Potentiometry, Formation constants
IdentifiersURN: urn:nbn:se:umu:diva-8974DOI: doi:10.1002/1099-0682(200007)2000:7<1509::AID-EJIC1509>3.0.CO;2-7OAI: oai:DiVA.org:umu-8974DiVA: diva2:148645