Combined HPLC-ICP-AES technique as an informative tool for the study of heteropolyniobates

Pavel A. Abramov, Tamara E. Romanova, Victoria V. Volchek, Anna A. Mukhacheva, Nikolay B. Kompankov, Maxim N. Sokolov

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The combined HPLC-ICP-AES technique was applied to study formation of tungstoniobates and phosphomolybdoniobates. Reaction of potassium hexaniobate with tungstic acid results in the formation of mixed Nb/W Lindqvist hexametalates. The metal ratio depends on the relative amount of H2WO4 and reaction time. The most favored species are [Nb4W2O19]6- and [Nb3W3O19]5- which equilibrate with hexaniobate. Formation of [Nb2W4O19]4- was also observed; its share gradually increases with increasing amount of tungstic acid and decreasing pH. Reaction of tungstic acid with telluropentaniobate [TeNb5O19]7- results only in substitution of W for Te producing the same mixed Nb/W Lindqvist anions, but with different distribution of the individual species. The reaction of phosphomolybdic acid (H3PMo12O40) with a niobium oxalate complex, [NbO(C2O4)2(H2O)2]-, leads to the formation of mixed P/Nb/Mo Keggin anions, unambiguously detected for the first time. Only [PMo11NbO40]4- and [PMo10Nb2O40]5- were observed over the whole concentration range. No trisubstituted [PMo9Nb3O40]6- was detected in the substitution reaction, but is accessible from the self-assembly reaction of the niobium oxalate complex, phosphoric acid, and molybdate.

Original languageEnglish
Pages (from-to)7949-7955
Number of pages7
JournalNew Journal of Chemistry
Volume42
Issue number10
DOIs
Publication statusPublished - 21 May 2018

Keywords

  • INDUCTIVELY-COUPLED PLASMA
  • CAPILLARY-ELECTROPHORESIS
  • MASS-SPECTROMETRY
  • PHOTOCATALYTIC PROPERTIES
  • EMISSION-SPECTROMETRY
  • LIQUID-CHROMATOGRAPHY
  • AQUEOUS-SOLUTIONS
  • COMPLEXES
  • CLUSTERS
  • IONS

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