NaNO3和NaClO4在N,N-二甲基甲酰胺中的离子溶剂化

利用红外光谱研究了NaNO₃和NaClO₄在N,N-二甲基甲酰胺(DMF)溶剂中发生离子-溶剂和离子-离子的相互作用, 分析结果表明, DMF的OC-N谱带发生了明显的变化. 定量计算了在Na⁺浓度为0.22~1.24 mol/kg范围内的溶剂化数为1~4. 对谱图中酰胺基上C-N和CO的特征峰强度随Na⁺浓度变化的对比, 推测离子溶剂化作用导致DMF的酰胺基内部形成共轭键. 利用量子化学方法进行优化及热力学性质计算, 得到C-N键伸缩振动频率及红外光谱强度变化规律. 优化结构与实验结论相符合. 由NaNO₃的ν₂谱带及NaClO₄的ν₁谱带的解析得到溶液中阴离子缔合效应的一般规律, 并通过阴离子缔合特征峰与酰胺基上的N-C-N面外振动峰(865 cm^-1)的变化情况, 讨论了溶液中的离子溶剂化作用.

Ionic Solvation of NaNO3 and NaClO4 in N,N-Dimethylformamide Solvent

Interaction of ion-solvent and ion-ion in N,N-dimethylformamide solution of NaClO4 and NaNO3 were investigated using IR spectroscopy. The characteristic absorption band intensities of C—N band and CO band were contrasted on amide group by the increasing of sodium ion concentration. The ν2 band of NaNO3 and the ν1 band of NaClO4 indicated the law of ion association. To compared with N—C—N vibration peak(865 cm-1), based on the deconvolution and quantitative calculation on obtained spectra, solvation numbers 1—4 of Na+ is calculated. Moreover the optimization and thermodynamic properties calculated by quantum chemistry obtained optimized structures consistenting with experiment. It had been found that the band of amide group obviously changed. Ion solvation possibly led to a new conjugated bond in the interior of amide group. We discussed the ion association of solution to explain the change of the structure by dimethylformamide.