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使用了量子化学计算方法在HF/6-31+G*水平下对高氯酸镁溶液中的高氯酸根水合,可能存在的离子缔合物种以及离子缔合过程进行了研究.高氯酸根的第一水合层至少需要6个水分子才能填满,在水合数6以下时,每增加一个水分子可以造成v1-ClO-4频率1.7cm-1的蓝移.高氯酸根与第一个无水镁离子结合可以造成较大的红移,与第二个和第三个镁离子结合后,可使v1-ClO-4频率连续的反向蓝移,这种变化与镁离子的极化作用相关.高氯酸根与水合镁离子可形成水合的缔合物种,包括溶剂共享离子对、接触离子对、溶剂共享型三离子团簇和接触型三离子团簇,其中溶剂共享型离子对和含有两个高氯酸根和一个镁离子的三离子团簇,可对v1-ClO-4频率造成较小的蓝移,与实验的拉曼光谱符合较好.高氯酸镁在溶液浓度升高时发生的离子缔合过程被推测为:自由水合离子→溶剂共享型离子对→含有两个高氯酸根的溶剂共享型三离子团簇→六水合高氯酸镁晶体,这一过程与硫酸镁有较大不同而与硝酸镁接近.
Quantum chemical calculations were used to study the hydration of perchlorate hydrate in magnesium perchlorate solution, possible ion-association species and ion-association processes at the HF / 6-31 + G * level. The first hydration layer requires at least 6 water molecules to fill, and for each additional water molecule below 6 hydration, a blue shift of 1.7 cm "1 in v1-ClO-4 frequency can result. The combination of water and magnesium ions can cause a larger redshift, which, in combination with the second and third magnesium ions, causes a continuous blue-reverse of the v1-ClO-4 frequency, which is related to the polarization of magnesium ions The perchlorate and hydrated magnesium ions can form hydrated associative species including solvent-shared ion pairs, contact ion pairs, solvent-sharing tri-ion clusters, and contact-type triionic clusters, where the solvent- Two perchlorate and one magnesium ion tri-ion clusters can cause a small blue-shift of the frequency of v1-ClO-4, which is in good agreement with the experimental Raman spectrum.High magnesium perchlorate concentration The occurring ion association process is presumed to be: free hydrated ions → solvent-shared ion pairs → Solubilized tri-ionic clusters containing two perchlorates → magnesium perchlorate hexahydrate crystals, which are quite different from magnesium sulfate and close to magnesium nitrate.