一种多核配合物稳定常数的简便测定方法

A Simple Method for Determining Stability Constants of Poly-nuclear Complexes

提出了一种测定多核配合物累积稳定常数的简便方法。即在保持配体A自由配体浓度恒定的条件下,逐渐滴定加入金属离子M,将金属离子总浓度对数值lgCM对自由金属离子浓度负对数pM作一阶偏微分图,找出偏微分值等于被测多核配合物MaAb中金属离子M的配位数负值-a时对应的pM和lgCM;应用公式:lgβMaAb=lgCM+apMr=-a+bpA-lga得到MaAb累积稳定常数对数值lgβMaAb的初值,再将初值代入公式:lgβMaAb=lgCM+apMr=-a+bpA-lga+lgMaAb,max得到新的lgβMaAb值,逐步迭代至两次结果相等即为最后计算结果。两种多核配合物体系被用于计算,计算结果与真实验值一致。

A simple method for determining stability constants of poly-nuclear complexes was presented in this paper.The method is based on addition of metal ion by titration at constant free ligand concentration.It includes the following several steps： firstly,draw the first-order partial differential diagram of logarithmic value of total concentration of metal ion in solution,lg CM against negative value of free metal ion concentration,pM;secondly,find the pM s and corresponding lgCM s at the pM points when their slopes equal to the coordination numbers of metal ion in poly-nuclear complex,MaAb;thirdly,obtain the initial values of cumulative stability constants of MaAa from the equation：lg βMaAb=lg CM＋apMr=-a＋bpA-lg a;fourthly,put these initial values into equation and obtain new lg βMaAb：lg βMaAb=lg CM＋apMr=-a＋bpA-lg a＋lg MaAb,max Continue to iterate until the two successive results are equal and they are the final results.The imaginary data of two poly-nuclear complexes were used for calculation,and their results agree with pre-set values.