@misc{oai:niigata-u.repo.nii.ac.jp:00005280, author = {Gagabe, Gene Frederick Dela Cueva}, month = {Mar}, note = {Complexes of lanthanoid ions (Ln^3+) have been extensively studied because of their increasing applications. One of the most widely used extracting agents for Ln^3+ is the bidentate β-diketone (HA). In this study, the extraction of the entire series of Ln^3+ with various β-diketones was systematically investigated. The β-diketones with substituent that have the least steric effect (tfa^-), planar aromatic moiety (tta^-, bta^- and nta^-), and bulky t-butyl moiety (pta^-) were used in this study. The extraction constants of LnA_3, K_ex, increase across the Ln^3+ series. The K_ex value of LnA_3 complexes are dependent on the molar volume of the HA in accordance with the regular solution theory. Addition of neutral Lewis base such as polyethers (POE) enhances the extraction of Ln^3+ by the formation of LnA_3POE complex. Polyethers having different topology, that is, cyclic (CE) or linear (DEOn), were considered. Extraction results confirmed that 1:1 adduct of LnA_3 with either cyclic or linear polyether was formed for all Ln^3+ ions. The formation constants of LnA_3(POE) in the organic phase, β_add, were determined and the variations were discussed in terms of the structures of these complexes. ^1H-NMR spectroscopy was employed to elucidate the structures of the complexes in solution. The changes in chemical shift of methylene protons of POE by addition of the adduct complex Ln(tta)_3(POE) were measured at various Ln^3+-to-POE concentration ratios. Results revealed that the oxygen atoms at the hydroxyl terminal of linear POE have higher tendency to coordinate to the metal ion in Ln(tta)_3 complex. Three (for La^3+) or two (for Lu^3+ or Y^3+) oxygen atoms of the POE coordinate to the metal ion without substitution of tta^- ligands. In the case of 18-membered CE complexes, La^3+ is incorporated inside the cavity of the POE, displacing one tta^- ligand from the inner coordination sphere while the other two remain coordinated to La^3+., On the other hand, for the adduct complex of Y^3+ with CE, all three tta^- ligands are directly coordinating to the metal ion. The existence of different structures of the complexes of CE across the Ln^3+ series was further corroborated by substitution extraction experiments. The effect of substituents of HA on the formation of LnA_3(DEOn) was also discussed. The β_add of bta^- and nta^- complexes is similar with those of tfa^- complexes, indicating that planar aromatic rings do not sterically hinder the formation of the ternary complex. The higher values of β_add for the complexes of tta^-, which has a slightly dipolar thenoyl moiety, can be accounted for the presence of ligand-ligand interaction. The formation constants of the ternary complexes of pta^- were lower compared to complexes of other β-diketones because of steric effect due to the bulky t-butyl moiety., 新潟大学大学院自然科学研究科, 平成23年3月23日, 新大院博(理)甲第332号, 新大院博(理)甲第332号}, title = {Thermodynamics and Structures of Ternary Complexes of Rare Earth Ions with β-Diketones and Polyethers}, year = {2011} }