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N-苯氨基乙酸和 N-萘氨基乙酸与铜(Ⅱ)和镍(Ⅱ)在25℃时生成络合物的逐级生成常数曾用电势滴定法予以测定。实验在30%(体积)乙醇溶液中及有0.10M 高氯酸钠存在下进行。为便于比较,也在相同条件下测定氨基乙酸与铜和镍的络合物。N-苯氨基乙酸络合物的稳定性最小,由于络合剂的硷性太弱之故。实验结果表明镍的络合物具四面体结构,N-萘氨基乙酸镍的顺磁性亦证明此点。铜(Ⅱ)与氨基乙酸和 N-苯氨基乙酸的络合物为平面型结构(dsp~2,共价键),但 N-萘氨基乙酸铜却因位阻效应而改变其平面型结构,可能为四面体或变形的 dsp~2型结构。在30%乙醇溶液中,由于溶剂的介电常数降低,络合物的稳定性增强。
The stepwise formation constant of the complex formed by N-phenylaminoacetic acid and N-naphthylaminoacetic acid with copper (II) and nickel (II) at 25C has been determined by potentiometric titration. The experiments were carried out in 30% ethanol by volume with 0.10M sodium perchlorate. For ease of comparison, the complex of glycine with copper and nickel was also determined under the same conditions. The stability of the N-phenylaminoacetic acid complex is minimized due to the weak basicity of the complexing agent. The experimental results show that the nickel complexes have a tetrahedral structure and the paramagnetic properties of N-naphthylaminoacetic acid nickel also prove this point. The complex of copper (Ⅱ) with glycine and N-phenylaminoacetic acid has a planar structure (dsp ~ 2, covalent bond). However, due to the steric effect, the planar structure of copper (Ⅱ) May be tetrahedron or deformed dsp ~ 2 structure. In the 30% ethanol solution, the stability of the complex is enhanced due to the decrease of the dielectric constant of the solvent.