Structural Insights into the Coordination and Extraction of Pb(II) by Disulfonamide Ligands Derived from o-Phenylenediamine
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- 作者：Robert J. Alvarado ; Jay M. Rosenberg ; Aileen Andreu ; Jeffrey C. Bryan ; Wei-Zhong Chen ; Tong Ren ; and Konstantinos Kavallieratos
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：October 31, 2005
- 年：2005
- 卷：44
- 期：22
- 页码：7951 - 7959
- 全文大小：167K
- 年卷期：v.44,no.22(October 31, 2005)
- ISSN：1520-510X
文摘
The o-phenylenediamine-derived disulfonamide ligands 1 and 2 complex and efficiently extract Pb(II) from waterinto 1,2-dichloroethane via ion-exchange, in combination with 2,2'-bipyridine (97.5% and 95.0%, respectively, for1:1 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.1H 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 sitesand a stereochemically active lone pair on Pb. The X-ray structure of 3 shows a pseudo trigonal bipyramidalconfiguration 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 patternwith two DMSO molecules is observed in the structure of 4·[2(CH3)2SO)], thus rationalizing the high solubility ofthe binary complexes in strongly coordinating solvents. In contrast, the X-ray structure of the ternary complex 5reveals 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 
S=O stretching frequencies shift to lower values in the binary Pb(II)-sulfonamido complexes andare again altered upon formation of the ternary Pb(II)-sulfonamido-bipy complexes, as would be expected for2,2'-bipy complexation and hindered S=O-Pb coordination.
S=O stretching frequencies shift to lower values in the binary Pb(II)-sulfonamido complexes andare again altered upon formation of the ternary Pb(II)-sulfonamido-bipy complexes, as would be expected for2,2'-bipy complexation and hindered S=O-Pb coordination.