具有Keggin结构的多元杂多化合物的合成与光谱研究Ⅱ

The Synthesis and Spectral Study of Multicomponent Heteropoly Compounds with Keggin Structure.Ⅱ

本文合成了一些具有Keggin结构的Si V Mo W四元杂多阴离子 [SiVxMoyW12 x yO4 0 ]( 4+x) -的化合物 (其中 ,x =1,2和 3) ,并对其进行了红外光谱研究 ,可看到化合物的M =Od,M Ob M和M Oc M的红外伸缩振动峰随着V原子数目的增加而红移 ;而钨原子数目的增加一般使之蓝移 ,因此推测出杂多化合物的酸性随着V数目的增加而减弱 ,氧化反应性能则相反。这种变化规律与 [PVxMoyW12 -x -yO4 0 ]( 3 +x) -相似。另外 ,可看到P系列的多元杂多酸 (或杂多化合物 )

The multicomponent heteropoly compounds 4+x [SiV xMo yW 12-x-yO 40]·n H 2O with Keggin structure have been synthesized and characterized by FTIR. The vibrational frequencies of containing-oxygen bonds ( Si-O a ,M=O d , M-O b-M and M-O c-M ) in these heteropoly compounds have been studied. The vibrational frequencies ν as(M=O d) and ν as(M-O b-M) are demonstrated to explain why the acidity of the heteropoly compounds becomes weaker and the oxidative ability becomes stronger when W atoms are substituted by V atoms.The rule of the change is similar with [PV xMo yW 12-x-yO 40] (3+x)-.In addition, the acidity of P series is stronger than the acidity of the corresponding Si series.