Near infrared study of aqueous lanthanide perchlorates

The near infrared spectra of water in aqueous solutions of La(ClO₄)₃, Pr(ClO₄)₃, Nd(ClO₄)₃, Gd(ClO₄)₃, Er(ClO₄)₃, Yb(ClO₄)₃, Lu(ClO₄)₃, and NaClO₄ have been measured in the concentration range from 0.3 to 2.5 mol-dm^–3, at 25°C. The relative contents of free OH groups in the 1.0, 1.6, and 2.2M solutions have been calculated from extinction coefficients for water at 1160 nm. They increase with increasing salt concentration and are greater in solutions of the lighter lanthanide perchlorates at any fixed molarity. The results are discussed in terms of the stoichiometry and structure of hydrated cations of trivalent lanthanides.     

Extraction of rare-earth nitrates by phosphoryl podands

The distribution of trace amounts of rare-earth nitrates between aqueous solutions of NH₄NO₃ and organic solutions of phosphoryl podands is studied for Ln = La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. The stoichiometry of the extraction complexes is determined. The effect of the structure of the extractant and the nature of the organic solvent on the efficiency of rare-earth recovery to the organic phase is considered.     

The sorption properties of carbon nanotubes modified with tetraphenylmethylenediphosphine dioxide in nitric acid media

The distribution of microamounts of La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between aqueous solutions of HNO₃ and multiwalled carbon nanotubes noncovalently modified with tetraphenylmethylenediphosphine dioxide (L) was considered depending on the concentration of HNO₃ in the aqueous phase and L in the sorbent phase. Ln(III) ions were shown to pass to the sorbent phase in the form of solvated nitrates Ln(NO₃)₃L₃. The effectiveness of the extraction of such complexes decreases along the series of rare-earth metals as the atomic number of the element in the Periodic Table increases.     

Determination of rare-earth eleemnts in rock samples by neutron activation analysis

A Ge(Li) detector combined with cation exchange separation has been used for the determination of 12 rare-earth elements (La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu) in rock samples by neutron activation analysis. After purification by the conventional hydroxide-fluoride precipitation, the rare-earth elements are separated into two fractions, light (La-Tb) and heavy (Ho-Lu), by EDTA cation exchange, and the γ-activities of the two fractions are measured by a Ge(Li) detector. The heavy rare-earths, such as Ho, Er, and Tm, can be easily γ-counted without serious interference from the intense Compton background and photopeaks due to the light rare-earths such as¹⁴⁰La,¹⁵³Sm,¹⁵²Eu, and¹⁶⁰Tb. The chemical yields (60%) for the individual rare-earths are determined by a reactivation technique. The results obtained for the U.S. Geological Survey standard rocks G-1 and W-1 are compared with the previously reported data.     

Determination of rare earths and thorium in apatites by thermal and epithermal neutron-activation analysis

A procedure is described for the non-destructive determination of Na, Mn, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu and Th in apatites by thermal and epithermal neutron-activation of independent portions of the material. The method was applied to three apatites with different contents. The precision obtained was better than +/-5% for La, Ce, Sm, Eu, Gd, Tb and Dy and +/-20% for Yb, Nd, Ho, Er and Lu for an apatite with a total rare-earth oxide content of the order of 1%. Determination of Ce, Tb and Yb could only be carried out with thermal neutron-activation analysis, while Gd, Ho and Er could only be determined after irradiation with epithermal neutrons.     

Extraction of rare earth elements with functionalized ionic liquid, 1,11-bis(1-methylimidazol-3-yl)-3,6,9-trioxaundecane bis(hexafluorophosphate)

Interfacial distribution of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y between aqueous solutions of their salts and solutions of functionalized ionic liquid, 1,11-bis(1-methylimidazol-3-yl)-3,6,9-trioxaundecane bis(hexafluorophosphate) has been studied. The stoichiometry of extracted complexes has been determined, the effect of HNO₃ concentration in aqueous phase on the efficiency of rare earth elements(III) recovery into organic phase has been considered.     

Quantum-chemical calculations of the tautomeric forms of azo derivatives of acetylacetone and determination of the stability constants of their complexes with rare-earth metals

The effective atomic charges in the tautomeric forms (enol-azo, keto-azo, and hydrazo) of 3-(2-hydroxy-5-nitro-3-sulfophenylazo)pentane-2,4-dione (L¹), 3-(2-hydroxy-3,5-disulfophenylazo)pentane-2,4-dione (L²), 3-(5-chloro-2-hydroxy-3-sulfophenylazo)pentane-2,4-dione (L³), 3-(2-hydroxy-4-nitrophenylazo)pentane-2,4-dione (L⁴), and 3-(2-hydroxyphenylazo)pentane-2,4-dione (L⁵) were calculated by the Hückel method (MO LCAO). It was found that the hydrazo form is most reactive for meta- and meta’-substituted derivatives (L^1–3) and the keto-azo form is most reactive for para-substituted (L⁴) and unsubstituted ones (L⁵). The stability constants of complexes of rare-earth metals (La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) with L^1–5 determined by potentiometric titration decrease in the order: Lu > Yb > Tm > Er > Ho > Dy > Tb > Gd > Eu > Sm > Nd > Ce > La. Functionalization of the aromatic part of ligands L affected neither the rare-earth metal: L ratio (1: 2) nor the above order of the stability constants.     

Determination of dissociation constants for some pyrogallol azo derivatives and stability constants of their complexes with rare-earth metals

The dissociation constants of some haloazo derivatives of pyrogallol and the stability constants of their complexes with rare-earth metals (La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) are determined by potentiometric titration in aqueous ethanol (3: 7). A correlation between the dissociation constants of the reagents and the stability constants of their complexes is found.     

Reactions and phases within the TeO2-rich part of the Bi2O3-TeO2 system

The complexes of heavy lanthanides and yttrium with 2,3-dimethoxybenzoic acid of the formula: Ln(C₉h₉O₄)₃·nH₂O, where Ln=Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III), Lu(III), Y(III), and n=2 for Tb(III), Dy(III), Ho(III), Y(III), n=1 for Er(III), Tm(III), n=0 for Yb(III) and Lu(III) have been synthesized and characterized by elemental analysis, ir spectroscopy, thermogravimetric studies and x-ray diffraction measurements. The complexes have colours typical for Lnł³⁺ ions (Tb(III), Dy(III), Tm(III), Yb(III), Lu(III), Y(III) - white; Ho(III) - cream and Er(III) - salmon). the carboxylate groups in these complexes are a symmetrical, bidentate, chelating ligand or tridentate chelating-bridging. they are isostructural crystalline compounds characterized by low symmetry. On heating in air to 1273 k the 2,3-dimethoxybenzoates of heavy lanthanides and yttrium decompose in various ways. The complexes of Tb(III), Dy(III), Ho(III), Er(III), Tm(III) and Y(III) at first dehydrate to form anhydrous salts which next are decomposed to the oxides of the respective metals. 2,3-dimethoxybenzoates of Yb(III) and Lu(III) are directly decomposed to oxides. When heated in nitrogen the hydrates also dehydrate in one step to form the anhydrous complexes that next form the mixture of carbon and oxides of respective metals or their carbonates. The solubility of the yttrium and heavy lanthanide 2,3-dimethoxybenzoates in water at 293 k is of the order of 10^-2 mol dm^-3. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preparation and photoluminescence properties of RE:Na3La9O3(BO3)8 (RE=Er, Yb) crystals

Using Na₂CO₃-H₃BO₃-NaF as fluxes, transparent RE:Na₃La₉O₃(BO₃)₈ (abbr. RE:NLBO, RE=Er, Yb) crystals have been grown by the top seed solution growth (TSSG) method. The X-ray powder diffraction analysis shows that the RE:NLBO crystals have the same structure with NLBO. The element contents were determined by molar to be 0.64% Er³⁺ in Er:NLBO, 2.70% Yb³⁺ in Yb:NLBO, respectively. The polarized absorption spectra of RE:NLBO have been measured at room temperature and show that both Er:NLBO and Yb:NLBO have a strong absorption bands near 980 nm with wide FWHM (Full Wave at Half Maximum) (21 nm for Er:NLBO and 25 nm for Yb:NLBO). Fluorescence spectra have been recorded. Yb:NLBO has the emission peaks at 985 nm, 1028 nm and 1079 nm and the emission peak of Er:NLBO is at 1536 nm. Spectral parameters have been calculated by the Judd-Ofelt theory for Er:NLBO and the reciprocity method for Yb:NLBO, respectively. The calculated values show that Er:NLBO is a candidate of 1.55 μm laser crystals and Yb:NLBO is a candidate for self-frequency doubling crystal.     

Extraction of rare earth elements with phosphoryl-containing lariat crown ether in the presence of ionic liquids

Interfacial distribution of rare earth elements (REE) La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y between aqueous solutions of their nitrates and solutions of the lariat crown ether 1,4,10,13-tetraoxa-7,16-diaza(diphenylphosphinylmethyl)cyclooctadecane in dichloroethane was studied in the presence of the ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide. The stoichiometry of extracted complexes was determined; the effect of HNO₃ concentration in the aqueous phase and the nature of extractant and ionic liquid on the extraction efficiency of REE(III) was considered.     

Extraction of rare-earth elements from nitrate solutions by fullerene black impregnated with tetraphenylmethylenediphosphine dioxide

The distribution of trace amounts of La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between HNO₃ aqueous solutions and fullerene black (a product of electric are evaporation of graphite) impregnated with tetraphenylmethylenediphosphine dioxide (L) as a function of the concentrations of HNO₃ in the aqueous phase and L in the sorbent phase was considered. It was shown that REE(III) ions pass into the sorbent phase in the form of Ln(NO₃)₃L₃ solvated nitrates; the efficiency of extraction of these ions decreases with an increase in the REE atomic number in the periodic table.     

Herstellung von Seltenerdcyaniden

Zusammenfassung Seltenerd-cyanoargentateM[Ag(CN)₂]₃ wurden hergestellt (M=La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er und Y), die aus wäßriger Lösung mit 3–4 Mol H₂O kristallisieren. Pr-cyanoargentat wurde entwässert und mit Li reduziert; hierbei konnte das in Tetrahydrofuran (THF) unlösliche Pr(CN)₃ im Gemisch mit anderen Stoffen erhalten werden. Da sich LiCN als inTHF löslich erwies, wurde die Herstellung aus AgCN und Li inTHF in Gegenwart von Naphthalin verbessert. LiCN wurde mit Seltenerdbromid-THF-Solvaten inTHF umgesetzt; hierbei fielen die bisher unbekannten einfachen Erdcyanide aus, die sehr zersetzlich sind und nach dem Trocknen die ZusammensetzungM(CN₃)· ·2THF besaßen (M=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm Yb, Lu und Y). Die Umsetzung verläuft bei den Verbindungen der Ceriterden schwieriger als bei denen der Yttererden; die Cyanide von La und Ce wurden nur mit überschüssigemTHF erhalten.

---

Rare-earth cyanoargentatesM[Ag(CN)₂]₃ were prepared (M=La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Y), crystallising from aqueous solution with 3–4 moles of water. Pr-cyanoargentate was dehydrated and reduced with Li yielding some Pr(CN)₃, insoluble in tetrahydrofurane (THF), in mixture with other substances. Because LiCN proved to be soluble inTHF, the preparation from AgCN and Li inTHF in the presence of naphthalene was refined. LiCN was reacted with rare-earth bromide-THF-solvates inTHF, whereupon precipitation occured of the hitherto unknown, very sensitive to moisture simple rareearth cyanides, which after drying had the compositionM(CN)₃· ·2THF (M=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y). The reaction is more difficult with the lighter lanthanon bromides than with the heavier ones; the cyanides of La and Ce were prepared only with excessTHF.

---

---

Mit 1 Abbildung     

A hydrogen-1, nitrogen-15, and chlorine-35 NMR coordination study of Lu(ClO4)3 and Lu(NO3)3 in aqueous solvent mixtures

A coordination study of Lu(III) has been carried out for the nitrate and perchlorate salts in aqueous mixtures of acetone-d₆ and Freon-12 by¹H,¹⁵N and³⁵Cl NMR spectroscopy. At temperatures lower than –90°C, proton and ligand exchange are slow enough to permit the direct observation of¹H resonance signals for coordinated and free water molecules, leading to an accurate measure of the Lu(III) hydration number. In perchlorate solution, in the absence of inner-shell ion-pairing, Lu(III) exhibits a maximum coordination number of six over the allowable concentration range of study, contrasting markedly with the report of values of six to nine or greater as determined by a similar NMR method. The absence of contact ion-pairing was confirmed by³⁵Cl NMR chemical shift and linewidth measurements. Extensive ion-pairing was observed in the nitrate solutions as reflected by the lower Lu(III) hydration numbers of two to three in these systems, the observation of two coordinated water signals, and¹⁵N NMR signals for two complexes. The¹H and¹⁵N NMR spectra and the hydration number could be accounted for by the presence of (H₂O)₄Lu(NO₃)²⁺ and (H₂O)₂Lu(NO₃) ₂ ¹⁺ .     

1H and13C NMR studies on lanthanide complexes with proline and hydroxyproline

The formation and the mode of coordination of rare earth (Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu) complexes with proline and hydroxyproline have been investigated by¹H and¹³C NMR spectral techniques. It has been established that the nitrogen and the carboxyl group of the ligands are involved in complexation, and that the OH^– group of hydroxyproline does not participate in coordination.

---

¹H und¹³C NMR Untersuchungen an Lanthanid-Komplexen mit Prolin und Hydroxyprolin

Zusammenfassung Die Bildung und die Koordination von seltenen Erden (Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu) in Komplexen mit Prolin und Hydroxyprolin wurden mit Hilfe von¹H- und¹³C-NMR-Spektroskopie untersucht. Es wurde festgestellt, daß in den Komplexen der Stickstoff und der Carboxylsauerstoff der Liganden koordinieren. Die OH^–-Gruppe von Hydroxyprolin nimmt keinen Anteil an der Koordinierung.

     

4,4′-Dipyridyl complexes of rare-earth thiocyanates

4,4-Dipyridyl complexes of rare-earth thiocyanates of the formulaLn(4-dipy)₂(NCS)₃·5H₂O (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y, 4-dipy = 4,4-dipyridyl) have been synthesized. The IR spectra of these compounds and other physical properties are discussed. The thermal decomposition of some compounds (in the order Gd ÷ Lu) has been investigated.

---

4,4-Dipyridylkomplexe von Seltenerdmetallthiocyanaten

Zusammenfassung Es wurden 4,4-Dipyridylkomplexe des TypesLn(4-dipy)₂(NCS)₃·5H₂O mitLn = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu und Y dargestellt. Die IR-Spektren und andere physikalische Eigenschaften werden diskutiert und die thermische Zersetzung von einigen Verbindungen (in der Reihe Gd ÷ Lu) untersucht.

     

Extraction and sorption preconcentration of rare-earth elements(III) and scandium(III) with phosphorylmethyl-substituted butylphenylphosphinates from perchloric acid solutions

The interphase distribution of microamounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc perchlorates between aqueous HClO₄ solutions and solutions of bidentate phosphorylmethyl-substituted butylphenylphosphinates Oct₂P(O)CH₂P(O)Ph(OBu) (compound I) and Ph₂P(O)CH₂P(O)Ph(OBu) (compound II) in 1,2-dichloroethane is studied. The stoichiometry of extracted complexes is determined, and the efficiency of metal ion extraction into the organic phase is considered as a function of the HClO₄ concentration in the aqueous phase and the nature of the organic solvent. The possibility of concentrating rare-earth elements (REE)(III) and scandium(III) from HClO₄ solutions with the complexing sorbent synthesized by noncovalent immobilization of I and II compounds on a macroporuos polymer matrix is shown.     

Extraction of rare-earth,yttrium, and scandium perchlorates by podands bearing diphenylphosphorylacetamide terminal groups

Partition of trace amounts of metal (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc) perchlorates was studied between aqueous HClO₄ solutions and dichloroethane solutions of phosphorus podands bearing two Ph₂P(O)CH₂C(O)NH-terminal groups linked via di-and triethylene glycol spacers. The stoichiometry of extracted complexes was determined. The efficiency of metal ion recovery to the organic phase was studied as a function of aqueous HClO₄ concentration and nature of the organic solvent. The compounds synthesized have higher metal extraction capacities in HClO₄ solutions than (dibutylcarbamoyl)diphenylphoshine oxide. The utility of macroporous polymer sorbents impregnated by these podands for extracting and concentrating rare earth(III) and scandium(III) ions from aqueous perchlorate solutions was demonstrated.     

Extraction of rare earth elements with 2-[2'-(methoxydiphenylphosphoryl)phenyldiazenyl]-4-<Emphasis Type="Italic">tert</Emphasis>-butylphenol in the presence of 1-butyl-3-methylimidazolium and trioctylmethylammonium picrates

Extraction of micro amounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y with solutions of 2-[2'-(methoxydiphenylphosphoryl)phenyldiazenyl]-4-tert-butylphenol in 1,2-dichloroethane in the presence of 1-butyl-3-methylimidazolium and trioctylmethylammonium picrates has been studied. The stoichiometry of extracted complexes has been determined, the effect of HNO₃ concentration in aqueous phase on the efficiency of rare earth elements recovery into organic phase has been considered.     

Neue Pyridiniumchlorometallatverbindungen der Seltenerdelemente

Summary Reaction of the rare earth chlorides with pyridinium chloride in tetrahydrofuran (THF) under anhydrous conditions gave nearly insoluble precipitates of the composition (pyH)₃ RECl₆·THF (RE=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, and Lu). They were characterized by chemical analysis and IR spectroscopy; decompositionin vacuo was studied, yielding the hithero unknown complexes (pyH)₃ RECl₆ (RE=La, Ce, Pr, Sm, Tb, Ho, Y, Tm, and Lu).