Structural insights into the coordination and extraction of Pb(II) by disulfonamide ligands derived from o-phenylenediamine.
Structural insights into the coordination and extraction of Pb(II) by disulfonamide ligands derived from o-phenylenediamine.
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DOI：
10.1021/ic051103r
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发表时间：
2005-09
影响因子：
4.6
通讯作者：
R. Alvarado;Jay M. Rosenberg;Aileen Andreu;J. Bryan;Wei-zhong Chen;T. Ren;K. Kavallieratos
中科院分区：
文献类型：
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作者：
R. Alvarado;Jay M. Rosenberg;Aileen Andreu;J. Bryan;Wei-zhong Chen;T. Ren;K. Kavallieratos
邻苯二胺衍生的二磺酰胺配体1和2配合物与2,2′-联吡啶结合，通过离子交换有效地将Pb（II）从水中萃取到1,2-二氯乙烷中（配体与Pb的比例为1:1，分别为97.5%和95.0%）。分离并表征了相应的配体1和2（分别为3和4）的Pb(II)-磺胺二元配合物，以及与2,2′-联吡啶（分别为5和6）的三元配合物。(1)萃取后有机相的H NMR谱显示形成了三元pb -磺酰胺-双吡啶配合物。3、4和三元配合物5的x射线表征一致表明Pb上有四个主要配位和一个立体化学活性的孤对。3的x射线结构在Pb上显示出伪三角双锥体构型，其中孤对占据了一个赤道位，并通过轴向S=O-Pb配位形成了一种罕见的“半定向”配位聚合物。在4的结构中观察到两个DMSO分子具有相同的轴向S=O-Pb配位模式。[2(CH(3))(2)SO)]，从而使二元配合物在强配位溶剂中的高溶解度合理化。相比之下，三元配合物5的x射线结构显示出扭曲的四坐标构型，只有弱S=O-Pb配位导致二聚体的形成，从而解释了其在弱配位溶剂中的高溶解度。FT-IR光谱证实了x射线数据，因为配体nu(S)(=)(O)伸展频率在二元Pb(II)-磺胺配合物中移至较低的值，并且在三元Pb(II)-磺胺-bipy配合物形成时再次改变，正如2,2'-bipy络合和受阻S=O-Pb配位所期望的那样。
The o-phenylenediamine-derived disulfonamide ligands 1 and 2 complex and efficiently extract Pb(II) from water into 1,2-dichloroethane via ion-exchange, in combination with 2,2'-bipyridine (97.5% and 95.0%, respectively, for 1:1 ligand-to-Pb ratios). The corresponding Pb(II)-sulfonamido binary complexes of ligands 1 and 2 (3 and 4, respectively), and ternary complexes with 2,2'-bipyridine (5 and 6, respectively), were isolated and characterized. (1)H NMR spectra of the organic phases after extraction show the formation of ternary Pb-sulfonamido-bipy complexes. X-ray characterization of 3, 4, and the ternary complex 5 consistently demonstrates four primary coordination sites and a stereochemically active lone pair on Pb. The X-ray structure of 3 shows a pseudo trigonal bipyramidal configuration on Pb, with the lone pair occupying one of the equatorial sites, and the formation of an unusual "hemidirected" coordination polymer via axial S=O-Pb coordination. The same axial S=O-Pb coordination pattern with two DMSO molecules is observed in the structure of 4.[2(CH(3))(2)SO)], thus rationalizing the high solubility of the binary complexes in strongly coordinating solvents. In contrast, the X-ray structure of the ternary complex 5 reveals a distorted four-coordinate configuration with only weak S=O-Pb coordination leading to dimer formation, thus explaining its higher solubility in weakly coordinating solvents. FT-IR spectroscopy confirms the X-ray data, since the ligand nu(S)(=)(O) stretching frequencies shift to lower values in the binary Pb(II)-sulfonamido complexes and are again altered upon formation of the ternary Pb(II)-sulfonamido-bipy complexes, as would be expected for 2,2'-bipy complexation and hindered S=O-Pb coordination.