【摘要】 在络合剂与金属离子浓度比固定条件下 ,改变溶液的pH值 ,用示差脉冲极谱技术研究金属离子Bi(Ⅲ ) 邻吡啶甲酸络合物体系 .根据实验得到的极谱峰电流和峰电位随溶液pH的变化 ,设计合适的金属络合物体系模型 .极谱实验络合物形成曲线 (ECFC)和理论络合物形成曲线 (TCFC)被用来检验金属络合物体系模型和优化络合物稳定常数 .含有极谱实验参数 (峰电位的移动和峰电流的变化 )的实验络合物形成曲线是特定金属络合物体系的特征函数 .理论络合物形成曲线的计算是基于金属络合物体系的质量平衡方程 .通过求解体系的质量平衡方程及拟合实验络合物形成曲线 ,用计算机分析程序CFC II优化得到金属络合物的稳定常数及金属离子的各种形态分布图 .计算机分析结果表明 ,在所研究的pH范围内 ,溶液中存在五种金属络合物 :MHL、ML、ML2 、ML3、ML3(OH) ,其稳定常数 (log β)分别为 7.5 2± 0 .15、7.48± 0 .0 6、13 .94± 0 .0 2、18.12± 0 .0 3、2 6.78± 0 .0 3 .更多还原

【Abstract】 The Bi(Ⅲ) Ligand(pyridine 2 carboxylic acid) system was studied by the differential pulse polarography (DPP) at the fixed total ligand to total metal concentration ratio \∶\ and varied pH. An appropriate model for the metal complex system is designed according to polarographic peak parameters, that is, the observed shift in the peak potential and the change in the peak current with pH changes in the sample solution. The polarographic experimental complex formation curve (ECFC) and theoretical complex formation curve (TCFC) were used for checking the designed metal complex model as well as optimizing stability constants. The ECFC, in which experimental parameters (a shift in a peak potential and a variation in a peak current) are included, appears to be a characteristic function for a particular metal ligand system. The TCFC is a theoretical curve calculated from mass balance equations for the designed metal ligand model. Using the computer analytical program, stability constants of metal complexes and species distribution diagrams are obtained by solving the mass balance equations written for the metal complex system and fitting the complex formation curve. Five bismuth complexes MHL, ML, ML 2, ML 3, ML 3(OH), and their stability constants as logβ 7.52±0.15, 7.48±0.06, 13.94±0.02, 18.12±0.03 and 26.78±0.03 , respectively, are finally reported while the TCFC fits best the ECFC.更多还原