Structural and Chemical Effects of the Surrounding Cations and Coexisting Compounds on [M(α-PW11O39)2]n–

The effects of countercations and coexisting compounds on the molecular structure of the [M(α-PW11O39)2]n− polyanion were analyzed in terms of the repulsion and twisting of two [α-PW11O39]7– units. More specifically, it was found that two [α-PW11O39]7– ions approached one another upon reducing the ionic radius of M in [M(α-PW11O39)2]n−. The interactive twisting of the [α-PW11O39]7– units prevented mutual repulsion of the units containing terminal O atoms, and the tendency for approach and twisting of the [α-PW11O39]7– units varied as a function of the type of countercation and the presence of coexisting compounds. Overall, this study demonstrated that some interactions between the counteraction and coexisting compounds with [M(α-PW11O39)2]n− determined the molecular conformation and the isolated form of the polyanion.

本研究基于双[α-PW11O39]7–单元间的排斥作用与扭曲作用，分析了抗衡阳离子（countercation）及共存化合物对[M(α-PW11O39)2]n−多阴离子（polyanion）分子结构的影响。具体而言，研究发现：当[M(α-PW11O39)2]n−中中心金属M的离子半径减小时，两个[α-PW11O39]7–阴离子会彼此趋近。[α-PW11O39]7–单元间的相互扭曲作用，可抑制带有端基氧原子的单元之间的相互排斥；而[α-PW11O39]7–单元的趋近与扭曲趋势，会随抗衡阳离子的种类及共存化合物的存在状态发生变化。总体而言，本研究证实：抗衡阳离子与共存化合物同[M(α-PW11O39)2]n−多阴离子之间的部分相互作用，决定了该多阴离子的分子构象与孤立存在形式。