高浓度NaBF_4/DMF溶液中的离子溶剂化和离子缔合

Ion Solvation and Ion Association in High-Concentration of NaBF_4 /DMF Solutions

利用振动光谱技术和量子化学方法研究了NaBF4/DMF溶液中的离子缔合和离子溶剂化现象。DMF分子的谱带变化表明,Na+ 与DMF分子的相互作用是通过DMF分子羰基上的氧原子进行的。Na+ 的溶剂化层内含有4个DMF分子,呈近似的四面体结构。而BF-4谱带的变化表明,溶液中存在着离子缔合,有直接接触离子对生成。直接接触离子对的含量随溶液浓度增加而增大。

Ion solvation and ion association in solutions of NaBF4/DW were studied by infrared and Raman spectroscopy and ab initio quantum chemistry. It was found that the sodium cation interacts on oxygen atom of C=O group in DNIF molecules. The solvation number of Na+, four, was obtained according to the change analysis of CH3 rocking band. The splitting of the v, mode of BF4- anion indicates the presence of contact ion pairs. Ionic association degree increases with increasing molality of the salt. The solvated structure of Na+ and the geometry of Li+ BF4- ion pair were also suggested based on the ab initio calculations.