Studies on Ternary Heteropoly Acids in Analytical Chemistry

发现同多钼酸根阴离子与磷酸盐阴离子反应生成的无机杂多阴离子具有非常特殊的性质，可作为重元素和碱性元素的分析试剂。4A族元素中的每一个，诸如Ti(&lt；IV&>t；)、Zr(&lt；IV&>t；)、Hf(&lt；IV&>t；)、Th(&lt；IV&>t；和Ce；)和5A族元素，例如V(&lt；V&>；)、Nb(&lt；V&>；)和Ta(&lt；V&gt；)；)可取代其中一种钼元素，形成三元杂多阴离子。每个三元杂多阴离子的核磁共振波谱都显示出每个取代的重元素在其共振峰位置的特定化学位移。这一事实对于水介质中4A族和5A族元素的同时定量分析是非常有用的。研究了溶质-溶剂相互作用，找出了在有机溶剂中萃取每个三元杂多阴离子的经验参数。将这些参数应用于12-钼硅酸盐和12-磷钼杂多酸的选择性分离，以及二元杂多阴离子和三元杂多阴离子的选择性分离。用扩展X射线吸收精细结构分析了11-钼钒磷钒磷三元杂多阴离子中钼原子和三元杂多阴离子中钼原子周围的局域结构和钒原子周围的局域结构。

An inorganic heteropoly anion produced through the reaction of an isopoly molybdate anion with a phosphate one was found to have very specific character acting as an analytical reagent for heavy elements and alkali elements. Each of group 4A elements such as Ti( <IV> ), Zr( <IV> ), Hf( <IV> ), Th( <IV> ) and Ce( <IV> ) and group 5A elements such as V( <V> ), Nb( <V> ) and Ta( <V> ), in the periodic table, could be substituted for one of the molybdenum elements so as to form a ternary heteropoly anion. The nuclear magnetic resonance spectrum of each ternary heteropoly anion shows a specific chemical shift for each substituted heavy element in its resonance peak position. This fact is quite useful for simultaneous quantitative analysis of the group 4A and group 5A elements in the aqueous medium.The solute-solvent interaction was investigated to find out the empirical parameters for the extraction of each ternary heteropoly anion in organic solvents. These parameters were applied to the selective separation of 12-molybdosilicate and 12-molybdophosphate and also to that of the binary heteropoly anion and the ternary one.The local structure around the molybdenum atom in the binary heteropoly anion and the ternary one and that around the vanadium atom in the 11-molybdo-vanado-phosphate vanado-phosphate ternary heteropoly anion were examined by extended X-ray absorption fine structure analysis.