In this paper, paramagnetic shifts have been measured for all ~1H and ^(13)C nuclei of 5-sulfo- salicylic acid (SSA) in the presence of the lanthanide ions in the second half of the series. The ligand forms isostructu...In this paper, paramagnetic shifts have been measured for all ~1H and ^(13)C nuclei of 5-sulfo- salicylic acid (SSA) in the presence of the lanthanide ions in the second half of the series. The ligand forms isostructural complexes with these ions in aqueous solution. The separation of LISs was carried out by the use of the Reilley method and the calculated dipolar shifts were used to simulate the coordination structure of the complex. The result reveals that SSA is coordinated to lanthanide ion via two oxygens, one from the carboxylic group and the other from the phenolic group with Ln—O bond lengths equal to 2.47 . The lanthanide ion lies on the benzene plane and the carboxylic group is twisted 20°from the benzene ring. Of all the nuclei examined, those in the six-membered chelate ring experience significant dipolar interactions and contact interactions. Small |G/A| ratios were obtained for two protons five bonds away from the central lanthanide ion, which shows that the number of bonds alone cannot be used as a criterion for neglecting contact shifts in aromatic ligand.展开更多
基金This work was supported by the National Natural Science Foundation of China
文摘In this paper, paramagnetic shifts have been measured for all ~1H and ^(13)C nuclei of 5-sulfo- salicylic acid (SSA) in the presence of the lanthanide ions in the second half of the series. The ligand forms isostructural complexes with these ions in aqueous solution. The separation of LISs was carried out by the use of the Reilley method and the calculated dipolar shifts were used to simulate the coordination structure of the complex. The result reveals that SSA is coordinated to lanthanide ion via two oxygens, one from the carboxylic group and the other from the phenolic group with Ln—O bond lengths equal to 2.47 . The lanthanide ion lies on the benzene plane and the carboxylic group is twisted 20°from the benzene ring. Of all the nuclei examined, those in the six-membered chelate ring experience significant dipolar interactions and contact interactions. Small |G/A| ratios were obtained for two protons five bonds away from the central lanthanide ion, which shows that the number of bonds alone cannot be used as a criterion for neglecting contact shifts in aromatic ligand.
