Abstract: Six heteropolyanions belong to P-V-W and V-V-W Keggin structures were synthesized and their ³¹P, ⁵¹V, ¹⁷O NMR spectra were reported in this paper. For the PV_xW_12-xO₄₀^(x+3)-(x=1-4)anions, when x=l the ³¹P, ⁵¹V NMR spectra only contain a single line which is independent on the pH of thesoiution. While x ≥ 2, the number and species of the geometric isomers increase. Their chemical shifts δ_p and δ_v were closely related to the acidity of the solution and x, i. e. δ_p decreases and δ_v incrases respectively with the pH value of the solution and x increases. Finally, the effect of the protonation to the bridged oxygen is also. briefly discussed.

Key words: Heteropolyanions, NMR