Synthesis and Characterization of Vanadium Substituted Dawson-Type Heteropoly Acid (Mo, As)

Five novel vanadium substituted series of Dawson-type heteropoly acid H₇As₂Mo 17VO 62·10H₂O（l）,H₈As₂Mo 16V₂O 62·7H₂O（2）, H₉As₂Mo 15V₃O 62·8H₂O（3）,H₈As₂Mo 14V₄O 62H₂·7H₂O（4）, H₉As₂Mo 13V₅O 62H₂·10H₂O（5） were prepared respectively in aqueous solution. When magnetic stirring and pH meter monitoring, all reactants mixed and controled different pH, then the mixture was refluxed for 10?h, later extracted by aether when it cooled, finally, it could be recrystaled by 0.5% sulphuic acid solution, then yielded productions that we need. Compounds （1）-（5） were characterized by elemental analysis,thermogravimetic analysis （TGA）, infrared spectroscopy （IR）, ultraviolet and visible spectroscopy（UV-Vis）, X-ray powder diffraction analysis, 51V nuclear magnetic resonance （ 51V NMR） structure analysis. The study indicates that these compounds possess Dawson structures. 51V NMR spectra reveals that V atom is polar-site substituted indeed.