NEB与过渡金属元素二元配合物的pH电位法研究

Studies on the binary complexes of some transition metals with NEB by potentiometry

用精密pH电位法测定了在甲醇 水混合溶剂中配体氨三乙氧基三苯甲酸 (NEB)质子化常数 (2 5℃ ,I =0 .2 0mol·L- 1 NaCl) ,讨论了溶剂对质子化常数的影响 ,结果表明溶剂对质子化常数的影响呈线性关系。测定了NEB与部分过渡金属M(Ⅱ) (M =Cd、Co、Ni、Cu及Zn)二元配合物的稳定常数 ,实验数据处理用程序MINIQUAD - 82和MIQUV完成。在二元体系中存在的配合物物种有 112、111、110及 2 10型 (M2 + ∶NEB3- ∶H+ ) ,并且 111及 110型配合物稳定常数的变化规律Cd(Ⅱ) <Co(Ⅱ) <Ni(Ⅱ) <Cu(Ⅱ) >Zn(Ⅱ)符合Irving

The protonation constants of the ligand 2,2′,2″ nitrilotris(2,1 ethanediyloxy)tris benzoic aicd(NEB) and the stability constants of its transition metal M(Ⅱ)(M=Cd?Co?Ni?Cu and Zn) complexes were determined in methanol water mixture potentiometrically(25℃,I=0.20mol·L -1 NaCl).Computer program MAGEC?MINIQUAD 82 and MIQUV were used for calculation.The effect of methanol solvent on protonation constants was discussed.There are three or four types of binary complexes that have been ascertained as the models 112?111?110 and 210(M∶L∶H,L=deprotonated NEB,H=proton),the stability constants order of complexes 111 and 110 for metal ions,which was found to be Cd(Ⅱ)<Co(Ⅱ)<Ni(Ⅱ)<Cu(Ⅱ)>Zn(Ⅱ),having an Irving Williams order.