杂多阴离子的NMR和ESR研究——P-V-W Keggin阴离子的31P、51V、17O-NMR谱

本文合成了六种含有P-V-W和V-V-W Keggin结构的杂多阴离子,并研究了它们的³¹P、⁵¹V、¹⁷O-NMR谱,对于PV_xW_12-xO₄₀^(x+3)-(x=1~4)阴离子,当x=1时,³¹P和⁵¹V-NMR谱只有一条线,并且此线化学位移和pH无关。当x ≥ 2时,谱线数目随着x迅速增加,其原因是几何异构体的数目和类型迅速增加。它们的化学位移δ_p,和δ_v。依赖于溶液的酸性和x,即δ_p,随pH值和x增加而减少,而δ_v,却随pH和x的增加而增加。最后简短讨论了桥氧上质子化的影响。

NMR AND ESR STUDY OF HETEROPOLYANIONS THE 31P、51V、17ONMR SPECTRA OF P-V-W KEGGIN ANIONS

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.