物理化学学报 >> 1994, Vol. 10 >> Issue (04): 336-341.doi: 10.3866/PKU.WHXB19940410

研究论文 上一篇    下一篇

稀土(III)与不饱和冠醚配位作用的热力学性质

刘育, 鲁统部, 谭民裕, 井上佳久, 白子忠男   

  1. 中国科学院兰州化学物理研究所 兰州 730000|兰州大学化学系,兰州 730000|日本姬路工业大学物质科学系,678-12|应用化学系,671-22
  • 收稿日期:1992-08-28 修回日期:1993-03-15 发布日期:1994-04-15
  • 通讯作者: 刘育

Complexation Thermodynamics of Rare Earch(III) Nitrates with Stibeno-15-Crown-5 in Anhydrous Acetonitrile

Liu Yu, Lu Tong-Bu, Tan Min-Yu, Inoue Yoshihisa, Hakushi Tadao   

  1. Lanzhou Institute of Chemical Physics Academia Sinica, Lanzhou 730000| Department of Chemistry, Lanzhou University, Lanzhou 730000| Department of Material Science,Himeji Institute of Technology, Kamigori, Hyogo 678-12| Department of Applied Chemistry, Himeji Institute of Technology, Shosha, Himeji, Hyogo 671-22, Japan
  • Received:1992-08-28 Revised:1993-03-15 Published:1994-04-15
  • Contact: Liu Yu

摘要:

用量热滴定法测定了2,3-二苯基-烯-[2]-1,4,7,10,13-五氧杂环十五烷(以下称2,3-二苯基-烯-[2]-15-冠-5)与稀土(Ⅲ)硝酸盐(La,Ce,Pr,Nd,Sm,Eu)在无水乙腈溶液中,298.15 K时配位作用的热力学性质.化学计量法表明,所有的稀土硝酸盐均与不饱和冠醚形成了1:1的配合物.实验中,由联接的计算机直接算出了配位物的稳定常数和配合作用的焓,进而算出了吉布斯自由能和配位熵. 结果表明,2,3-二苯基-烯-[2]-15-冠-5与Pr(NO_3)_3形成的配位化合物,其稳定常数最高,并与15-冠-5的实验结果作了比较.从热力学的观点讨论了不饱和冠醚分子结构和阳离子的性质对配位稳定性的影响.

关键词: 稀土, 冠醚, 配位作用, 热力学性质, 无水乙腈溶液, 量热滴定

Abstract:

Calorimetric titrations have been performed in anthydrous acetonitrile at 298.15 K in order to obtain the complex stabillty constants(K_s) and the thermodynamic parameters for the complexation of rare earth(Ⅲ) nitrates (La, Ce, Pr, Nd, Sm, Eu) with 2,3-diphenyl-ene-(2)-1,4,7,10,13-pentaoxacyclopentadecane (Stilbeno-15-crown-5). The complexation stoichiometry is 1:1 for all rare earth(Ⅲ) nitrates. The complex stability constants (K_s), reaction enthalpies(△H~o) and entropies (△S~o) were calculated directly by using precision calorimeter connected to an personal microcomputer. The coordination of the unsaturated crown ether B (to see Fig.1) with Pr~(3+) showed the highest complexation ability and selectivity in the six kinds of rare earth (III) nitrates, and compared with the results of 15-crown-4A (in Fig.1). The thermodynamics quantities clearly indicate that the comples stability sequence is essentially entropy governed, although the complex formation itself is evidently enthalpy driven. The effects of unsaturated crown ether's molecular structure and cation's properties upon complex stability have been discussed from a viewpoint of thermodynamics.

Key words: Rare earth, Crown ether, Complexation, Thermodynamics, Calorimetric titration