物理化学学报 >> 1992, Vol. 8 >> Issue (06): 772-777.doi: 10.3866/PKU.WHXB19920611

研究论文 上一篇    下一篇

35Cl NMR研究溶液中离子对和离子缔合

李芝芬; 荆军平; 孙赋; 刘瑞麟   

  1. 北京大学物理化学研究所,北京 100871
  • 收稿日期:1991-07-13 修回日期:1992-01-15 发布日期:1992-12-15
  • 通讯作者: 李芝芬

35Cl NMR Study on Ion Pair and Ionic Solvation in Solution

Li Zhi-Fen; Jiang Jun-Ping; Sun Bin; Liu Rui-Lin   

  1. Institute of Physical Chemistry, Peking University, Beijing 100871
  • Received:1991-07-13 Revised:1992-01-15 Published:1992-12-15
  • Contact: Li Zhi-Fen

摘要: 测量了Sr和Ba高氯酸盐在乙腈和乙醇中0.5 mol·L~(-1)溶液的~(35)Cl NMR峰宽Δv和粘度η。按核四极矩弛豫机理, 结合文献中Mg~[1]和Ca~[2]盐的数据, 一种溶剂中各盐的Δv/η之比当反映~(35)Cl核处的电场梯度平方之比。按接触型离子对假设, ~(35)Cl处电场梯度平方之比应等于(r_++r_-)~(-6)。测得各盐的Δv/η之比与计算的(r_++r_-)~(-6)吻合, 论证了在乙腈与乙醇中为接触型离子对。同时文中报告了Δv/η和盐的摩尔电导随水或DMF加入的变化。

关键词: 弛豫速率, 电场梯度, 离子对, 离子溶剂化, 高氯酸盐

Abstract: This research has recorded the linewidth of ~(35)Cl of Sr(ClO_4)_2 and Ba(ClO_4)_2 at 0.5 mol·L~(-1) in acetonitrile and ethanol. In terms of nuclear quadrupole moment relaxation mechanism and together with the results for Mg(ClO_4)_2 and Ca(ClO_4)_2 in literature contact type of ion pair for perchlorate salts of alkali earth metals was argued. The linewidth of ~(35)Cl at fixed concentration of Sr (ClO_4)_2 and Ba(ClO_4)_2 in acetonitrile or ethanol as bulk solvent was measured as a function of [B]/[M~(2+)]. where B represents H_2O or DMF. The trend of the plot and the reason for that were explained and the solvation number for Sr~(2+) were estimated. Mole conductivities of salts were also measured and explained for supporting of contact ion pair.

Key words: Relaxation rate, Electric field gradient, Ion pair, Ionic solvation, Perchlorate salts