金属离子Na+,Li+及Mg2+与C1O4-和NO3-形成的无水离子缔合物种的从头算量子化学研究

采用量子化学计算方法在B3 LYP/6-311++G**水平下对Na+,Li+和Mg2+与ClO4-和NO3-形成的离子缔合物种的结构以及v1-频率进行了研究,并将结果与SO42-和上述3种阳离子形成的物种进行了对比.在缔合物种结构方面,当阳离子数目≤2时,与SO42-体系相似,ClO4-和NO3-主要与阳离子形成双齿缔合结构,而当阳离子数目＞2时,特别是具有2个正电荷的Mg2+离子数目较多时,由于阳离子间的斥力更大,与阳离 子结合能力较弱的ClO4-和NO3-较难与其形成稳定的离子团簇,而在SO42-体系中,则易形成单齿缔合结构.在v1-频率的变化趋势方面,3种阴离子形成的缔合物种大体相同,说明无水离子团簇的频率变化主要受阳离子性质和缔合结构影响.虽然阴离子性质也有部分影响,但不占主要地位.

Ab initio Investigation on Unhydrated Ion-associated Species Between Na+,Li+,Mg2+ Ions and ClO4-,NO3-

The structures of ion-associated species between Na+,Li+,Mg2+ ions and ClO-4,NO-3 were optimized via ab initio calculations.The influences of the cations to the ν1-frequencies were also investigated and compared with those in SO2-4 system.For the ion-associated structures,when the numbers of metal ions are not more than 2,the systems of ClO-4 and NO-3 are analogous to the SO2-4 system.That is,the bidentate associated structures are easy to form between the anions and cations.When the numbers of metal ions are more than 2,especially for the clusters with more Mg2+ ion which has more positive charge,the repulsions between metal ions will make the clusters instable in the ClO-4 and NO-3 systems,while more monodentate structures will form in the SO2-4 system.The influences of metal ions to the ν1-frequencies of all three anions are similar,which can confirm the changes of frequencies in unhydrated clusters are less influenced by the characteristic of anion but more by the polarization of cation and associated structures.