Speciation and coordination chemistry of uranyl(VI)-citrate complexes in aqueous solution.
Speciation and coordination chemistry of uranyl(VI)-citrate complexes in aqueous solution.
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DOI：
10.1021/ic0341800
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发表时间：
2003-09
影响因子：
4.6
通讯作者：
S. Pasilis;J. Pemberton
中科院分区：
文献类型：
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作者：
S. Pasilis;J. Pemberton
采用拉曼光谱、衰减全反射红外光谱和电喷雾质谱研究了柠檬酸与铀酰络合反应的pH依赖性。nu（s）（UO（2））包络的pH依赖性变化表明，在pH 2.0至9.5的范围内，存在三种U=O键长逐渐增加的主要UO（2）（2+）-柠檬酸盐络合物。第一种是铀酰（VI）在pH 3.0 - 5.0范围内的主要形式，在光谱等价的配位环境中含有两个UO（2）（2+）基团，对应于已知存在于该pH范围内的[（UO（2））（2）Cit（2）]（2）（-）络合物。在pH值>6.5时，[（UO（2））（2）Cit（2）]（2）（-）发生相互转化，形成[（UO（2））（3）Cit（3）]（3）（-）和（UO（2））（3）Cit（2）。ESI-MS研究不同的铀酰（VI）/柠檬酸盐的比例，pH值和溶液抗衡阴离子的解决方案被成功地用于确认复杂的化学计量。研究的铀酰和柠檬酸盐浓度范围为0.50至50 mM。
The pH dependence of uranyl(VI) complexation by citric acid was investigated using Raman and attenuated total reflection FTIR spectroscopies and electrospray ionization mass spectrometry. pH-dependent changes in the nu(s)(UO(2)) envelope indicate that three major UO(2)(2+)-citrate complexes with progressively increasing U=O bond lengths are present over a range of pH from 2.0 to 9.5. The first species, which is the predominant form of uranyl(VI) from pH 3.0 to 5.0, contains two UO(2)(2+) groups in spectroscopically equivalent coordination environments and corresponds to the [(UO(2))(2)Cit(2)](2)(-) complex known to exist in this pH range. At pH values >6.5, [(UO(2))(2)Cit(2)](2)(-) undergoes an interconversion to form [(UO(2))(3)Cit(3)](3)(-) and (UO(2))(3)Cit(2). ESI-MS studies on solutions of varying uranyl(VI)/citrate ratios, pH, and solution counteranion were successfully used to confirm complex stoichiometries. Uranyl and citrate concentrations investigated ranged from 0.50 to 50 mM.