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应用pH法,在25.0±0.1℃,0.1M NaClO_4,30％(V/V)乙醇水溶液中,测定了以邻菲罗啉(phen)为第一配体(A),N-(对位取代苯基)氨基乙酸(p-RphG;R=CH_3O,CH_3,H,Cl:G=NHCH_2COOH)为第二配体(B)的Cu(Ⅱ),Ni(Ⅱ),Co(II),Zn(Ⅱ)三元配合物的生成常数1ogK_(MAB)~(MA).结果表明,三元配合物的稳定性与第二配体的酸碱强度之间存在着直线自由能关系,即logK_(MAB)~(MA)=apK_B+C.文章讨论了影响三元配合物稳定性的各种因素.三元配合物稳定性的增加可以用金属离子与phen之间形成π反馈键来解释.与二元体系比较,Ni(Ⅱ)和Zn(Ⅱ)的三元配合物稳定性增长更大.此现象可以用π反馈键的生成以及分子内配体的芳环之间的重叠来解释.
The results showed that phenanthroline (phen) as first ligand (A), N- (para-substituted (II), Ni (II), Co (II), Zn (II), and Zn (II) for the second ligand (B) Ⅱ) The formation constants of the ternary complex are 1ogK_ (MAB) ~ (MA) .The results show that there exists a linear free energy relationship between the stability of the ternary complex and the acid-base strength of the second ligand, ie logK_ (MAB) ) ~ (MA) = apK_B + C.This paper discusses various factors affecting the stability of ternary complexes.The stability of ternary complexes can be explained by the formation of π-feedback bond between metal ions and phen. The stability of the ternary complex of Ni (Ⅱ) and Zn (Ⅱ) increased more than that of the ternary system. This phenomenon can be explained by the formation of π-feedback bonds and the overlap between the aromatic rings of the intramolecular ligands.