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本文报道了三种具有Lindqvist结构的还原杂多阴离子ESR谱,在室温和适合的pH范围内,VMo_5O_(19)~(4-)的溶液ESR谱含有8条超精细线而V_2W_4O_(19)~(5-)和V_3W_3O_(19)~(6-)则具有15条超精细线,这种15条谱线的形状会逐渐变化。长期放置后它会变成8条线,我们用计算机成功地模拟了这些复杂的8+15条谱线,得到了一系列不同8线和15线比例的模拟谱。文中也测定了77K冷冻谱的ESR参数并计算了近似的K、α值,把所得的结果与Keggin结构杂多阴离子的K、α值进行比较后发现:Keggin结构的K,α值较小,原因是Keggin结构中存在有角共享的氧原子增加了未偶电子的额外离域性。
Three ESR spectra of reduced heteropolyanion with Lindqvist structure were reported in this paper. The solution ESR spectrum of VMo_5O_ (19) ~ (4-) contained 8 hyperfine lines and V_2W_4O_ (19) ~ (5-) and V_3W_3O_ (19) ~ (6-) have 15 hyperfine lines, and the shapes of these 15 lines gradually change. After long-term placement, it becomes eight lines. We successfully simulated these complex 8 + 15 lines with a computer and obtained a series of analog spectra with different 8-line and 15-line ratios. The ESR parameters of the 77K cryogenic spectrum were also measured and the approximate values of K and α were calculated. The results were compared with the K and α values of heteropolyanions of Keggin structure. The results showed that the K and α values of Keggin structure are small, The reason is that the existence of angular shared oxygen atoms in the Keggin structure increases the extra delocalization of non-dipole electrons.