【摘要】 由下述反应形成三元配合物体系其配合物稳定常数的测定比较困难,这是因为形成反应与分解反应紧密相连,有时甚至重叠。本文以汞(Ⅱ)-甲基百里酚蓝-X(SCN~-,Be~-,I~-)为例,探讨了两个方法:其-为改变实验设计,然后用经典的离解度法求得稳定常数,方法简便,适于分解反应较弱的情况;其二为先求得分解反应的平衡常数,而后计算前一式的稳定常数,此法不论分解反应强或弱均可使用,但推算较繁。更多还原

【Abstract】 The process of forming ternary complexes and their decomposition may proceed according to the following pattern: The determination of stability constants of complexes is comparatively difficult, due to the fact that the formation and decomposition reactions are closely connected. At times, they may even overlap. This renders the application of classical saturation method impossible. Among the recently reported methods of determination, it is still unable to solve this problem when the decomposition reaction is rather strong.Meanwhile, the evaluation procedure is also not strict enough. With mercury (II)-methyl thymol blue-X(SON, Br,I) as example, two methods are investigated in this paper. The first one bases on the variation experimental design, so that classical method of degree of dissociation can be used to calculate the stability constant from the molar ratio curve obtained. This method is simple, adaptable to cases where the decomposition is relatively weak. The second method requires the preliminary acquisition of the equilibrium constant of the decomposition reaction,with the calculation of the stability constant of the preceding formation reaction thereon. The evaluation procedure is more strict. This method is applicable whether the decomposition reaction is strong or weak. Thus, we obtain stability constants of ternary complexes with rather strong subsequent decomposition reaction, such as Hg·MTB·I. Results obtained are rather satisfactory.更多还原