Hypersensitivity in the 4f .fwdarw. 4f absorption spectra of neodymium(III) complexes in aqueous solution

Stephens, Eileen M.; Schoene, Karl; Richardson, F. S.

doi:10.1021/ic00180a004

Cited by 33 publications

(14 citation statements)

References 6 publications

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“…These transitions are especially sensitive probes of the Nd coordination environment, able to distinguish between small differences in the coordination environment. 25,32,33 The excellent agreement between the spectra taken in the IL and dodecane provides strong evidence that the extracted Nd-HDEHP complexes, and hence those of other trivalent lanthanide and actinide cations, are the same in these two solvents. We also measured the spectrum of lower concentrations of Nd (ca.…”

Section: Optical Spectroscopymentioning

confidence: 73%

Identical extraction behavior and coordination of trivalent or hexavalent f-element cations using ionic liquid and molecular solvents

et al. 2005

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The extraction of both UO2(2+) and trivalent lanthanide and actinide ions (Am3+, Nd3+, Eu3+) by dialkylphosphoric or dialkylphosphinic acids from aqueous solutions into the ionic liquid, 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide has been studied and compared to extractions into dodecane. Radiotracer partitioning measurements show comparable patterns of distribution ratios for both the ionic liquid/aqueous and dodecane/aqueous systems, and the limiting slopes at low acidity indicate the partitioning of neutral complexes in both solvent systems. The metal ion coordination environment, elucidated from EXAFS and UV-visible spectroscopy measurements, is equivalent in the ionic liquid and dodecane solutions with coordination of the uranyl cation by two hydrogen-bonded extractant dimers, and of the trivalent cations by three extractant dimers. This is the first definitive report of a system where both the biphasic extraction equilibria and metal coordination environment are the same in an ionic liquid and a molecular organic solvent.

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Section: Optical Spectroscopymentioning

confidence: 73%

Identical extraction behavior and coordination of trivalent or hexavalent f-element cations using ionic liquid and molecular solvents

et al. 2005

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“…In all of the complexes examined, including those of Am(III), , the 4f → 4f or 5f → 5f transitions move to longer wavelengths upon formation of complexes with nitrogen donor ligands, as is the case for the f → d transitions of Ce(III). This is expected from the observation that in the Nd(III) complexes with ligands containing various numbers of oxygen and nitrogen donors the hypersensitive bands in the absorption spectra showed the strongest responses only to ligands containing nitrogen donors.…”

Section: Results and Discussionmentioning

confidence: 64%

Evidence for Participation of 4f and 5d Orbitals in Lanthanide Metal–Ligand Bonding and That Y(III) Has Less of This Complex-Stabilizing Ability. A Thermodynamic, Spectroscopic, and DFT Study of Their Complexation by the Nitrogen Donor Ligand TPEN

et al. 2022

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The formation constants (log K 1 ) of lanthanide(III) (Ln) ions [except for Pm(III)] and the Y(III) cation have been measured with the ligand TPEN (N,N,N′,N′-tetra-2-picolylethylenediamine). These log K 1 values show a typical variation with ionic radius, with a local maximum at Sm(III) and a local minimum at Gd(III), with an overall increase in log K 1 from La(III) to Lu(III) as the ionic radius decreases. The log K 1 for the Y(III)/TPEN complex is much lower than expected from its ionic radius, while the literature log K 1 for Am(III) is much higher. The latter effect is thought to be due to greater covalence in the M−L (metal−ligand) bond than for Ln(III) ions: the low log K 1 for Y(III) is interpreted as being due to lower covalence. The f → f transitions in the Nd(III) and Pr(III) complexes were examined for effects that might indicate the participation of f orbitals in M−L bonding. The intensity of the f → f transitions in the Nd(III)/TPEN complex was greatly increased compared to that of the Nd 3+ aqua ion, which appeared to be due to additional sharp peaks, possibly parity forbidden transitions where parity rules were broken by covalence in the M−L bond. The Pr(III)/TPEN complex showed that all of the f → f transitions shifted to longer wavelengths by some 5 nm, with modest increases in intensity. The effects seen in the f → f transitions of Nd(III) and Pr(III) with TPEN with its six nitrogen donors were present to a much smaller extent in the EDTA and other complexes with fewer nitrogen donors. The changes in the f → f transitions of the TPEN complexes of Er(III) and Ho(III) were small, suggesting a smaller contribution of f orbitals to M−L bonding in these heavier Ln(III) ions. The intense Laporte allowed f → d transitions in Ce(III) complexes show large shifts to longer wavelengths as complexes of, for example, EDTA with increasing numbers of nitrogen donors, suggesting the participation of both f and d orbitals, or either, in M−L bonding. The nature of M−L bonding in M(III)/TPEN complexes was further investigated via density functional theory calculations.

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“…In fact, the Nd and Am spectra and the Eu fluorescence measurements taken after the addition of lactate match those previously reported for binary M(DTPA) 2-complexes. [25,[31][32][33] Both prior work [15,32,[34][35][36] and our experiments with the Nd-CDTA-oxalate system (Fig. 1a) 3 and ligand protonation are the same as those used by Nilsson and Nash.…”

Section: Discussionmentioning

confidence: 70%

Do Aqueous Ternary Complexes Influence the TALSPEAK Process?

Leggett

Liu

Jensen

2010

Solvent Extraction and Ion Exchange

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The aqueous speciation of trivalent lanthanide and actinide cations in solutions containing DTPA (diethylenetriamine-N,N,N 0 ,N 0 ,N 00 -pentaacetic acid) and lactic acid were studied under conditions representative of the TALSPEAK process. Spectrophotometric titrations, fluorescence spectroscopy, and thermometric titrations were used to search for indications of ternary metal-DTPA-lactate complexes. The addition of lactate anions to metal-DTPA complexes was undetectable by any of these techniques, even at free lactate concentrations of 0.75 M. Although lactic acid is necessary for the optimal performance of the TALSPEAK process, we find that the fractions of aqueous ternary Ln 3+ /An 3+ -DTPA-lactate complexes are far too low to account for the observed acid dependence of TALSPEAK metal extraction.

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Hypersensitivity in the 4f .fwdarw. 4f absorption spectra of neodymium(III) complexes in aqueous solution

Cited by 33 publications

References 6 publications

Identical extraction behavior and coordination of trivalent or hexavalent f-element cations using ionic liquid and molecular solvents

Identical extraction behavior and coordination of trivalent or hexavalent f-element cations using ionic liquid and molecular solvents

Evidence for Participation of 4f and 5d Orbitals in Lanthanide Metal–Ligand Bonding and That Y(III) Has Less of This Complex-Stabilizing Ability. A Thermodynamic, Spectroscopic, and DFT Study of Their Complexation by the Nitrogen Donor Ligand TPEN

Do Aqueous Ternary Complexes Influence the TALSPEAK Process?

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