溶液中某些镉(Ⅱ)的混合配体配合物的稳定性研究——关于混合配体配合物相对稳定性定量表征的讨论  

Study on the Formation and Stability of Ternary Complexes of Cadmium (Ⅱ) with Vitamin D_3 and Some N, N-Bidentate Ligands in Solution——A Discussion on Quantitative Expression of the Relative Stabilities of Ternary Complexes

作　　者：张锋[1] 刘祁涛[1] 

机构地区：[1]辽宁大学化学系,沈阳110036

出　　处：《化学学报》1993年第3期251-256,共6页Acta Chimica Sinica

基　　金：国家自然科学基金

摘　　要：本文用pH电位法研究了在70％(v/v)乙醇-水溶液中Cd(Ⅱ)与维生素D_3(VD_3)和乙二胺(en)或2,2′-联吡啶(bipy)在37±0.1℃和离子强度为0.10(KNO_3)条件下,三元混配配合物的稳定性.结果表明,上述混合配位体系均形成稳定的1:1:1型混配配合物,且△log K值均为较大的正值(分别为+1.06和+1.54),但相应的logX值却并不很大(分别为2.18和2.83).从统计效应和配合物分子内的配体间疏水相互作用,讨论了造成这种反常结果的可能原因,并针对如何判断三元混配配合物相对稳定性高低等问题提出了作者的见解.The formation and stability of the ternary complexes of Cd(II) with Vitamin D_3 (VD_3) and some N, N-bidentate ligands: ethylenediamine (en) or 2, 2'-bipyridyl (bipy) have been studied by potentiometric pH titrations in a 70% (v/v) ethanolwater solution at 37±0.1℃ and 0.10 ionic strength (KNO_3). Both of the systems form stable ternary complexes, and the ⊿log K values of those complexes are all abnormally high (+1.06 and+1.54 respectively). On the contrary, the log X values of the same complexes only have the normal size (2.18 and 2.83 respectively), not corresponding to the large ⊿log K. The possible reasons that lead to these results have been discussed from the viewpoint of statistical effects and the intramolecular ligand-ligand hydrophobic interactions presented in the binary and ternary complexes. Some new ideas in comparing the stabilities of ternary and the 1:1 binarycomplexes have been proposed and discussed.

关 键 词：维生素D3 镉 溶液 络合物 稳定性 

分 类 号：O614.242[理学—无机化学]