稀土乙酰丙酮络合物的拉曼光谱(Ⅱ)

RAMAN SPECTRA OF RARE EARTH ACETYLACETONATE COMPLEXES (Ⅱ)

本文从拉曼光谱观察水合分子对无水、一水、三水稀土乙酰丙酮络合物的金属—氧(M—O)拉伸振动带的影响,发现无水络合物在400cm^(-1)附近只有一个振动带,一水络合物在400和415cm^(-1)附近有两个强度不等的振动带,它们的M—O振动频率随原子序数变化都呈“四分组”效应,而三水络合物400cm^(-1)附近带变形,且随轻、重稀土而异,从而干扰了镧系变化规律,没有系统的“四分组”效应。由于一水络合物415cm^(-1)附近带随脱水而消失,吸水而复现的可逆实验事实,修正了前文对415cm^(-1)附近带的指定,而归属于(M—O)H_(2)。络合物M—O拉伸带随水合分子变化反映灵敏,出现特征带形。

Laser Raman spectra of the rare earth acetylacetonate anhydrous, mono and trihydrated complexes indicated that hydrated molecules have effects on the M-O stretching vibration bands of these complexes. It was found that anhydrous complexes have only one band near 400cm^(-1), mono-hydrated complexes have two bands of the different intensities near 400 and 415cm^(-1), and that the M-O stretching vibration frequencies of them change periodically with atomic number, showing the "tetrad effect" . However, the band near 400cm^(-1) of trihydrated complexes undergoes deformation and different changes with the light and heavy rare earth ion, therefore, the "tetrad effect" characteristic of lanthanide was disturbed and destroied. When monohydrated complexes loses coordination water molecule, the band near 415cm^(-1) disappears, and if dehydrated complex absorbs water molecule in air, this band again appears. Assignment of the band near 415cm^(-1) in the last paper was modified on the basis of the above-mentioned invertible experimental fact, it is due to ( M-O ) H_(2).