【摘要】 本文从配位平衡出发,从光度法对单核、逐级配位配合物的实验研究入手,导出了包含配合物逐级稳定常数为未知数、体系中各物质初始浓度为已知条件的非线性目标函数。对该目标函数用最优化方法求算出配合物的逐级稳定常数的最优估值,利用光度与组分的浓度关系又求得配合物摩尔吸光系数的估计值。采用本手段以平衡移动法研究了5—磺基水杨酸铁(Ⅲ)配位平衡体系的各级稳定常数与摩尔吸光系数,用等摩尔系列法研究了其第一级稳定常数和摩尔吸光系数,取得了满意的结果。更多还原

【Abstract】 When a coordination equilibrium is MRn-1+R MRn, we can express stability constant Kn as follow:1/Ka=[MRσ-1]·[R]/[MRa]M is metallic ion,CMα-1 is initial mole concertration of MRa-1 , and CB is initial mole concentration of ligand R. It follows thatCMn-1=MRn-1+ MRn and Cg = [R] + [MRa]. From above equations, we can obtain thatAssume that MRa,MRa-1 and R are all color species in the system,and their absorbance are DMBa, DMRa-1 and Dg. It is not difficult to getthatderived from the Lambert-Beer’s low, where D is the absorbance of the whole system and ∈ is the mole absorbance coefficient of the same system. For m groups of initial conditions, coordinate equilibrium absorbance can be meassured using and , ΔDi(i≠j ; = 1,2, 3……m; j=1, 2, 3……m).It is easy to derive following equation;Assume that MRa, MR4-1 and R are all color species in the system, and their absorbance are DMRn, DMRa-1 and DC.It is not difficult to get that let the right hand of above equation is /, then the value of Kn is equivalent to that of object function F(1/Kn),which can be solved by using nonlinear programe under condition ofIf Kn is obtained in this way, for any initial concentration CM1N-1 ,CN1 andcorresponding ΔD1, mole absorbance coefficient ∈n can be obtained from the relation between ΔD1 and [MRn].We have studied the coordination compound Fe(SSA), Fe(SSA)2 and Fe(SSA)s system to give the verification of this method. The results are satisfactory.We have also treated the photometric data of unstable coordination compound Ta-PAR system under condition of pH = 5.50, and found that logrithm of apparent stability constant was 5.10±0.07,mole absorbance coefficient was 1.85×104±0.04×104 (the value in a literature is 1.67×104).Comparing with some other methods of photometric analysis e.g.linear method, graptic solution and etc., this method has following advantages.1 .It is not necessary to determine e value first and then Kn value by experiments. We can obtain both ∈n and Ka by using photometric experiment in terms of optimization. The information can be made full use of.2 . This method can be used to derive stability constant and mole absorbance coefficient of stable and unstable coordination compound.3 . This method can be applied to treate several kinds of photometric experiments data e.g.Job’s method and method of equilibrium change experiment etc.更多还原