ⅡB族金属离子-5-取代邻菲罗啉-二酮肟配体三元体系的 稳定性研究

在(35±0.1)℃,I=0.1mol·dm^-^3KNO~3条件下,用pH法测定了二酮肟配体PnAO,5-取代邻菲罗啉(5-Rphen,R=CH~3,H,Cl,NO~2)的质子化常数,Zn(Ⅱ),Cd(Ⅱ),Hg(Ⅱ)分别与PnAO和5-Rphen二元体系的稳定常数,以及Zn(Ⅱ),Cd(Ⅱ),Hg(Ⅱ)-PnAO-5-Rphen三元体系的稳定常数。实验结果表明,在上述二元、三元体系中均存在良好的直线自由能关系,并从三元配合物构型上讨论了存在线性关系的内在原因。同时,讨论了金属离子、取代基对配合物稳定性的影响。

Study on the Stability of Group IIB Metal Ion-5-Substituted o- Phenanthroilne - Diketooxime Ternary Complexes

The protonation constants of 3, 3, 9, 9-tetramethyl-4, 8- diazaundecane-2, 10-dioxime (PnAO), the stability constants of Zn(Ⅱ), Cd(Ⅱ), Hg(Ⅱ)-PnAO, Zn(Ⅱ), Cd(Ⅱ), Hg(Ⅱ)-5-substituted o- phenanthroline binary complexes and Zn(Ⅱ), Cd(Ⅱ), Hg(Ⅱ)-PnAO- 5- substituted o-phenanthroline ternary complexes have been determined by pH titration method at (35±0.1)℃, I=0.1mol·dm^-^3 KNO~3. The results show that here exist Linear Free Energy Relationships (LFER) between the protonation constants of 5-substituted o-phenanthroline and the corresponding stability constants of Zn(Ⅱ), Cd(Ⅱ), Hg(Ⅱ) binary complexes as well as the relevant constants for the Zn(Ⅱ), Cd (Ⅱ), Hg(Ⅱ)-PnAO-5-substituted o-phenanthroline ternary system. The stability order for the title systems is generally shown by the following: Zn(Ⅱ)＞Cd(Ⅱ)＜ Hg(Ⅱ). The internal cause has been explored in terms of the charge/radius effect of the metal ions.