有机大阳离子与 H_nXW_(12)O_(40) (X=B,Si,P)多金属氧酸盐的合成及热行为(英文)  

Synthesis and Thermal Behavior for Polyoxo- metalates of Large Organic Cation with H_nXW_(12)O_(40) (X=B,Si,P)

作　　者：汪敦佳[1] 方正东[1] 韩德艳[1] 

机构地区：[1]湖北师范学院化学与环境工程系,湖北黄石435002

出　　处：《稀有金属材料与工程》2006年第2期205-208,共4页Rare Metal Materials and Engineering

基　　金：Foundation item: Supported the Natural Science Foundation of Hubei Province (No. 2003ABA062) and the Natural Science Foundation of the Educational Commission of Hubei Province (grant No. 2003A001)

摘　　要：合成了 3 种新的多金属氧酸盐 (CTMA)5BW12O40·8H2O, (CTMA)4SiW12O40·3H2O, (CTMA)3PW12O40·2H2O,利用元素分析、IR 光谱和 TG-DTA 技术对其进行了表征。IR 光谱表明这些化合物不仅含有 Keggin 型结构,而且存在有机大阳离子的特征吸收峰;TG-DTA 曲线显示它们的热行为是一个多步分解过程,首先这些化合物在大约 269℃以下脱去水分子,然后它们的无水多金属氧酸盐经历了两步或 3 步的分解过程,分别脱去 CTMA 分子及其碎片,并伴随 Keggin 型结构的塌陷。通过 XRD 和 IR 光谱确证其最终分解产物是一个含有 WO3与 B2O3, SiO2或 P2O5的混合物。同时还提出了这些化合物可能的热分解过程。Three new polyoxometalates, （CTMA）sBW12O40·8H2O, （CTMA）4SiW12O40·3H2O, （CTMA）3PW12O40·2H2O, were prepared from HnXW12O40·nH2O （X=B, Si, P） with cetyltrimethylammonium bromide （CTMAB,C16H33N（CH3）3Br） in aqueous solution, and characterized by elemental analysis, IR spectra and TG-DTA. The IR spectrum showed the identification of not only the presence of Keggin-type anion of heteropoly acids but also the characteristic functional group of large organic cation in these compounds. The TG/DTA curves indicated that their thermal decomposition was a more-steps process consisting of simultaneous processes involving also Keggin anion. At first, these compounds had a mass loss of water molecules at the temperature below -269℃, then the thermal decomposition of their anhydrous polyoxometalates had a two or three stages process, which corresponded to CTMA molecules, its fragments and heteropoly oxometallates decomposition. The end-product of thermal decomposition was a mixture of WO3 and B203, SiO2 or P205, confirmed by X-ray diffraction and IR spectroscopy. And the possible thermal decomposition mechanisms of the complexes are proposed.

关 键 词：多金属氧酸盐 热分解 TG-DTA IR XRD 

分 类 号：O621.25[理学—有机化学]