十一钨铜杂多钨硅酸盐位置异构体的合成、表征及性质

Synthesis,characterization and properties of undecatungstocupperates positional isomers

合成了通式为α-,βi-KnH6-n[SiW11Cu(H2O)O39].xH2O(βi=β1,β2,β3)的4种异构体,通过元素分析、IR光谱、UV光谱、极谱和循环伏安进行了表征。系统研究了它们在溶液中的电化学性质,提出了其还原机理,讨论了杂多酸阴离子的结构对其氧化还原性的影响,得出杂多阴离子的极谱半波电位顺序为β2>β1>β3>α,其还原过程包括铜的单电子还原和钨的双电子两质子加合过程。催化活性实验表明,合成化合物对烯烃环氧化反应具有良好的催化作用。

The four heteropoly isomers a-and βi-KnH6-n [ SiW11 Cu（H2O）O39 ]·xH2O（βi =β1, β2,β3 ） were prepared and characterized by elementary analysis, IR, UV spectrometry, polarography and cyclic voltammetry. Its electrochemical behavior in aqueous solution was systematically studied, and their reaction mechanism has been discussed.The effect of structure on the redox was investigated. The order of polarographic half-wave potential （E1/2） of heteropoly anions is as follows： β2 〉β1 〉 β3 〉 a. Its reduction process involves an one-electron reduction of Cu（ Ⅱ and a pair of two-electron reduction of W（ Ⅵ ）. Epolidation of maleic acid with H2O2 catalyzed by heteropoly positional isomers was studied, β3 isomers are the most active.