【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。更多还原

【Abstract】 Three new polyoxometalates, (CTMA)5BW12O40·8H2O, (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 B2O3, SiO2 or P2O5, confirmed by X-ray diffraction and IR spectroscopy. And the possible thermal decomposition mechanisms of the complexes are proposed.更多还原