Mutual solubility of the components in systems RED-1 diluent-tri-n-butyl phosphate solvates of rare-earth element(III) (Nd, Gd, Y, Yb, Lu) nitrates-Escaid 100 diluent

Phase diagrams of liquid binary systems RED-1 diluent-tri-n-butyl phosphate solvates of rare-earth element(III) (neodymium, gadolinium, yttrium, ytterbium, lutetium) nitrates were studied, and the binodal curves in the ternary systems [Ln(NO₃)₃(TBP)₃] (Ln = Nd and Yb)-RED-1-Escaid 100 were determined at various temperatures.     

Synthesis and luminescence properties of the Pr(III), Sm(III), Eu(III), Nd(III), and Yb(III) complexes with propane-1,3-dione derivatives

The luminescence method, mass spectrometry, and elemental analysis are used to reveal that under optimal conditions (pH 5–8) Ln³⁺ ions (Ln = Pr, Sm, Eu, Nd, and Yb) with 1-(2-hydroxy-4-methylphenyl)-3-(5-methyl-1-phenyl-¹ H-1,2,3-triazol-4-yl)propane-1,3-dione form complexes with the mole ratio Ln: ligand = 2: 3. According to the IR spectral data, Ln³⁺ ions coordinate three oxygen atoms of two carbonyl groups and one hydroxyl group. In the IR spectra of the complexes, an intense band at 628.7 cm^?1 is assigned to the Ln-O bond vibrations. The X-ray diffraction patterns of the complexes contain no lines corresponding to the ligand. The luminescence intensity of the complexes in the visible spectral range changes in the series Eu(III) > Sm(III) > Pr(III), whereas in the IR region the order is Yb(III) > Nd(III). In all cases, luminescence of the solid complexes is considerably more intense than that of their solutions.     

IR luminescence of neodymium(III) and ytterbium(III) ions in complexes with N-alkyl-substituted 2-aminobenzoic acids

The luminescence of neodymium(III) and ytterbium(III) ions in complexes with N-alkyl-substituted 2-aminobenzoic acids has been studied. The luminescence spectra of the Nd(III) complexes show two bands with maxima at 875 and 904 and 1060 nm, and the spectra of the Yb(III) complexes show one band at 980 nm. The introduction of an additional ligand or some surfactants into the Nd(III) and Yb(III) coordination sphere leads to an increase in the luminescence intensity. A correlation between the luminescence intensity of Nd(III) and Yb(III) 2(N-alkylamino)benzoates and the length of the hydrocarbon radical bound to the nitrogen atom has been studied.     

Schiff base derivatives of lanthanons,La(III), Pr(III), Nd(III) and Sm(III) complexes of bifunctional tetradentateSchiff base

Reactions of La(III), Pr(III), Nd(III) or Sm(III) nitrate with bifunctional tetradentateSchiff base, [o-HOC₆H₄C(CH₃): :NCH₂]₂, having the donor system HO–N–N–OH in 12 molar ratio have been investigated and found to yield new derivatives of the type [Ln(SBH₂)₂](NO₃)₃ [whereLn=La(III), Pr(III), Nd(III) or Sm(III) andSBH₂=Schiff base molecule, [o-HOC₆H₄C(CH₃) : NCH₂]₂. On the basis of elemental analyses, conductivity and magnetic measurements and infrared spectra, plausible structures for the resulting complexes have been indicated.     

Komplexverbindungen von Pr(III) und Nd(III) mit o-Hydroxybenzohydrazid und Salicylaldehyd

Reaction of Pr(III) and Nd(III) with o-hydroxybenzohydrazide yields either tris-(o-hydroxybenzohydrazidato) compounds of typeM(o-Bh)₃·3 H₂O, whereM(III) is Pr or Nd, or tris-(salicyladehydato) compounds: Pr(o-Bh)₃(Sald)₃· 4 H₂O, Pr(o-Bh)₆(Sald)₃ and Nd(o-Bh)₃(Sald)₃·2 H₂O, Nd(o-Bh)₆(Sald)₃. The metal to ligand ratio in the compounds formed with neutral o-hydroxybenzohydrazide was either 1∶3 or 1∶6, and their formation was followed spectrophotometrically. Compounds isolated were identified by elementary analysis and characterized by thermogravimetric analysis and IR-absorption spectroscopy. Coordination sites of o-hydroxybenzohdrazide are discussed with reference to the characteristic IR-absorption bands of the-CONHNH₂ and phenolic groups.     

Cyanide-bridged Os(II)/Ln(III) coordination networks containing [Os(phen)(CN)4]2- as an energy donor: structural and photophysical properties

Slow evaporation of aqueous solutions containing mixtures of Na 2[Os(phen)(CN) 4], Ln(III) salts (Ln = Pr, Nd, Gd, Er, Yb), and (in some cases) an additional ligand such as 1,10-phenanthroline (phen) or 2,2'-bipyrimidine (bpym) afforded crystalline coordination networks in which the [Os(phen)(CN) 4] (2-) anions are coordinated to Ln(III) cations via Os-CN-Ln cyanide bridges. The additional diimine ligands, if present, also coordinate to the Ln(III) centers. Several types of structure have been identified by X-ray crystallographic studies. Photophysical studies showed that the characteristic emission of the [Os(phen)(CN) 4] (2-) chromophore, which occurs at approximately 680 nm in this type of coordination environment with a triplet metal-to-ligand charge transfer ( (3)MLCT) energy content of approximately 16 000 cm (-1), is quenched by energy transfer to those Ln(III) centers (Pr, Nd, Er, Yb) that have low-lying f-f states capable of accepting energy from the Os(II)-based (3)MLCT state. Time-resolved studies on the residual (partially quenched) Os(II)-based luminescence allowed the rates of Os(II) --> Ln(III) energy transfer to be evaluated. The measured rates varied substantially, having values of >5 x 10 (8), approximately 1 x 10 (8), and 2.5 x 10 (7) s (-1) for Ln = Nd, Er or Yb, and Pr, respectively. These differing rates of Os(II) --> Ln(III) energy transfer can be rationalized on the basis of the availability of f-f states of the different Ln(III) centers that are capable of acting as energy acceptors. In general, the rates of Os(II) --> Ln(III) energy transfer are an order of magnitude faster than the rates of Ru(II) --> Ln(III) energy transfer in a previously described series of [Ru(bipy)(CN) 4] (2-)/Ln(III) networks. This is ascribed principally to the lower energy of the Os(II)-based (3)MLCT state, which provides better spectroscopic overlap with the low-lying f-f states of the Ln(III) ions.     

2-methylaminopyridine N-oxide complexes from some lanthanide(III) perchlorates

2-Methylaminopyridine N-oxide (HL) complexes of the formula [M(HL)₇](ClO₄)₃ (M = Sm), [M(HL)₆(H₂O)_n](ClO₄)₃ (MPr, Eu, Ho, Yb; n = 0, or 1) and [M(HL)₅(H₂O)_n](ClO₄)₃ (MNd, Dy, Er; n = 0 or 2) have been prepared and characterized. Only the Pr(III) and Nd(III) solids contain water molecules which DSC and TGA studies suggest are present as aquo ligands. All solids were isolated as microcrystalline powders from 4:1 ligand-to-metal ion mole ratio mixture in isopropanol; methanol solutions yielded oils. The solids possess the color of the respective aquated metal ions and behave as 1:3 electrolytes in acetonitrile. The IR spectral study shows that the four lighter metal ions have some amine coordination while the four heavier metal ions are coordinated exclusively by N-oxide oxygens. Electronic spectra recorded in the solid state as well as in acetonitrile solution are also discussed.     

Highly efficient near-infrared-emitting lanthanide(III) complexes formed by heterogeneous self-assembly of Ag(I), Ln(III), and thiacalix[4]arene-p-tetrasulfonate in aqueous solution (Ln(III) = Nd(III), Yb(III))

Heterogeneous self-assembly of thiacalix[4]arene-p-tetrasulfonate (TCAS), Ag(I), and Ln(III) (= Nd(III), Yb(III)) in aqueous solutions conveniently afforded ternary complexes emitting Ln(III)-centered luminescence in the near-infrared (NIR) region. A solution-state study revealed that the Ag(I)-Nd(III)-TCAS system gave a complex Ag(I)(4)·Nd(III)·TCAS(2) in a wide pH range of 6-12. In contrast, the Ag(I)-Yb(III)-TCAS system gave Ag(I)(2)·Yb(III)(2)·TCAS(2) at a pH of around 6 and Ag(I)(2)·Yb(III)·TCAS(2) at a pH of approximately 9.5. The structures of the Yb(III) complexes were proposed based on comparison with known Ag(I)-Tb(III)-TCAS complexes that show the same self-assembly behavior. In Ag(I)(2)·Yb(III)(2)·TCAS(2), two TCAS ligands sandwiched a cyclic array of a Ag(I)-Ag(I)-Yb(III)-Yb(III) core. In Ag(I)(2)·Yb(III)·TCAS(2), Yb(III) was accommodated in an O(8) cube consisting of eight phenolate O(-) groups from two TCAS ligands linked by two S-Ag-S linkages. Crystallographic analysis of Ag(I)(4)·Nd(III)·TCAS(2) revealed that the structure was similar to Ag(I)(2)·Yb(III)·TCAS(2) but that it had four instead of two S-Ag-S linkages. The number of water molecules coordinating to Ln(III) (q) estimated on the basis of the luminescent lifetimes was as follows: Ag(I)(4)·Nd(III)·TCAS(2), 0; Ag(I)(2)·Yb(III)(2)·TCAS(2), 2.4; and Ag(I)(2)·Yb(III)·TCAS(2), 0. These findings were compatible with the solution-state structures. The luminescent quantum yield (Φ) for Ag(I)(4)·Nd(III)·TCAS(2) was 4.9 × 10(-4), which is the second largest value ever reported in H(2)O. These findings suggest that the O(8) cube is an ideal environment to circumvent deactivation via O-H oscillation of coordinating water. The Φ values for Ag(I)(2)·Yb(III)(2)·TCAS(2) and Ag(I)(2)·Yb(III)·TCAS(2) were found to be 3.8 × 10(-4) and 3.3 × 10(-3), respectively, reflecting the q value. Overall, these results indicate that the ternary systems have the potential for a noncovalent strategy via self-assembly of the multidentate ligand, Ln(III), and an auxiliary metal ion to obtain a highly efficient NIR-emissive Ln(III) complex that usually relies on elaborate covalent linkage of a chromophore and multidentate ligands to expel coordinating water.     

Heteroligand complexes of Nd(III), Yb(III), and Er(III) dibenzoyl methanates with bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)methane

Heteroligand coordination compounds Ln(Dbm)₂HL · nEtOH, where Ln is Nd(III), Yb(III), and Er(III); HDbm is dibenzoylmethane; H₂L is bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)methane, are synthesized and studied. The complexes are studied by elemental analysis, TGA, and IR spectroscopy. The structure of complex [Nd(Dbm)₂ · HL · EtOH] · EtOH is determined by X-ray diffraction analysis. The crystals are triclinic, space group $P\bar 1$ , a = 10.2004(9), b = 11.3809(10), c = 20.9173(18) Å, α = 102.133(1)°, β = 103.568(1)°, γ = 100.306(2)°; Z = 2 (8416 reflections with I > 2σ(I), R = 0.053, Rw = 0.136). The luminescence of solid samples of the studied complexes is studied in the near-IR region.     

Extraction of Nd(III), Tb(III) and Lu(III) with picrolonic acid in methylisobutylketone

The extraction of Nd(III), Tb(III) and Lu(III) as representatives of lanthanide(III) ions with picrolonic acid (HPA) in methylisobutylketone (MIBK) has been studied from pH 1-2 buffer solutions. The composition of the organic species formed in the organic phase after extraction has been determined by slope analysis to be M(PA)₃ [M = Nd(III), Tb(III) and Lu(III)]. The equilibrium constant values, log k _ex This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and characterization of some novel ketazinates and aldazinates of Pr(III) and Nd(III):

The reactions of bifunctional tridentate azines (AZH₂) derived by the condensation of aldehydes or ketones and hydrazine hydrate with Pr(III) and Nd(III) isopropoxides in 1 : 1, 2 : 3 and 1 : 2 molar ratios in the medium of anhydrous benzene are described. The resulting Ln(OPrⁱ)(AZ), Ln₂(AZ)₃ and Ln(AZ)(AZH) [where Ln = Pr(III) or Nd(III)] types of coloured solids are non-electrolyte in anhydrous DMF. The isopropoxy group of 1 : 1 complexes has been found to undergo replacement reactions with excess of t-butanol. The monoisopropoxy metal azine complexes are dimeric whereas the 2 : 3 and 1 : 2 metal azine complexes are monomeric in boiling chloroform/benzene. Suitable structures based on elemental analysis, molecular weight determinations, conductance measurements and infrared, proton magnetic resonance and electronic spectral studies have been indicated for the newly synthesized compounds. The integral procedural decomposition temperature (IPDT) of bis-neodymium(III) tris-salicylaldehydeazine and bisneodymium(III) tris-o-hydroxyacetophenoneazine have also been calculated and this shows the lower thermal stability of the former as compared to the latter.     

Synthesis,spectral, antimicrobial,and thermal properties of Ce(III), Gd(III), Nd(III), Tb(III), and Er(III) gliclazide complexes

The complexation between the lanthanide metal ions Ce(III), Gd(III), Nd(III), Tb(III), and Er(III) and gliclazide produced 1 : 1 molar ratio metal: gliclazide (Glz) complexes coordinated in a monodentate fashion via the OH group and having the general formulas [M(Glz)Cl₃(H₂O)]·xH₂O (M = Ce, Gd, Nd and x = 1, 3, 4, respectively) and [M(Glz)(H₂O)₄]Cl₃·yH₂O (M = Tb, Er and y = 1, 2, respectively). The structure of the synthesized lanthanide gliclazide complexes was assigned by IR, ¹HNMR, and UV-Vis spectroscopy. Thermal analysis and kinetic and thermodynamic parameters gave evidence for the thermal stability of the Glz complexes. The latter showed a significant antimicrobial effect against some bacteria and fungi.     

Synthesis and characterization of Pr(III), Nd(III) and Er(III) complexes with 2,6-pyridinedimethanol

The reactions of Ln(NO₃)₃?6H₂O (Ln=Pr, Nd or Er) with the potentially tridentate O,N,O chelating ligand 2,6-pyridinedimethanol (H₂pydm) in a 1:2 M ratio were investigated, and complexes with the formula [Ln(H₂pydm)₂(NO₃)₂](NO₃) (Ln=Pr or Nd) (1 and 2) and [Er(H₂pydm)₃](NO₃)₃ (3) were isolated. The compounds contain 10-coordinate Pr(III) and Nd(III) ions that crystallize in the triclinic space group P-1 while the 9-coordinate Er(III) complex crystallizes in the monoclinic system (P2₁/n). A new lanthanide complex, [Pr(H₂pydm)₃](Cl)₃?DMF (4), has been synthesized by reaction of PrCl₃?6H₂O and H₂pydm. The nine-coordinate Pr(III) is bound to three H₂pydm ligands. X-ray crystal structures of 1–4 reveal that the ligand coordinates tridentate via the pyridyl nitrogen and the two hydroxyl oxygens. The electronic absorption spectra of 1–4 show 4f–4f transitions.     

Copper(II)-lanthanoid(III)-copper(II) trinuclear complexes with N,N′-bis(2-aminopropyl)-oxamido ligand

Six novel μ-oxamido trinuclear complexes, namely Cu₂(oxap)₂Ln(ClO₄)₃ (Ln: La, Pr, Nd, Gd, Yb, Ho), where oxap is N,N′-bis(2-aminopropyl)oxamido, have been synthesized. The complex Cu₂(oxap)₂Gd(ClO₄)₃ was characterized with variable temperature magnetic susceptibility (4—300 K). The exchange integrals J (Cu—Gd) and J′ (Cu–Cu) were found to be 0.83 cm^?1 and ?1.62 cm^?1, indicating that very weakly ferromagnetic spin-exchange interaction operates between Cu(II) and Gd (III) ions.     

Extraction of Ce(III), Gd(III) and Yb(III) from Citrate Medium by High Molecular Weight Amines

Abstract

High molecular weight amines have been used for the extraction of citrate complexes of Ce(III), Gd(III) and Yb(III). The effect of different variables on extraction has been studied. The citrate species extracted in the organic phase have been proposed as [(RNH₃ ⁺)₃] [M(Cit)₂]^3-.     

4-Chloro-2-methoxybenzoates of heavy lanthanides(III) and yttrium(III)

4-Chloro-2-methoxybenzoates of heavy lanthanides(III) and yttrium(III) were obtained as mono-, di-, tri-or tetrahydrates with metal to ligand ratio of 1:3 and general formula Ln(C₈H₆ClO₃)₃·nH₂O, where n=1 for Ln=Er, n=2 for Ln=Tb, Dy, Tm, Y, n=3 for Ln=Ho and n=4 for Yb and Lu. The complexes were characterized by elemental analysis, FTIR spectra, TG, DTA and DSC curves, X-ray diffraction and magnetic measurements. The carboxylate group appears to be a symmetrical bidentate chelating ligand. All complexes are polycrystalline compounds. The values of enthalpy, ΔH, of the dehydration process for analysed complexes were also determined. The solubilities of heavy lanthanide(III) 4-chloro-2-methoxybenzoates in water at 293 K are of the order of 10⁻⁴ mol dm⁻³. The magnetic moments were determined over the range of 76–303 K. The results indicate that there is no influence of the ligand field of 4f electrons on lanthanide ions and the metal ligand bonding is mainly electrostatic in nature.     

The extraction of Yb(III) and Lu(III) with chloroform from aqueous solutions in the presence of cupferron

The equilibrium of distribution of Yb(III) and Lu(III) between chloroform and the aqueous phase in the presence of cupferron (the ammonium salt of N-nitrosophenylhydroxylamine) were studied as apH function of the aqueous phase and the concentration of N-nitrosophenylhydroxylamine (HL). The stability constants for theLnL _n ^3–n ) complexes (n=1÷3) being formed in the aqueous phase were established, as well as the equilibrium constants of the extraction reaction $$Ln(H_2 O)_m^{3 + } + 3HL_{(O)} \mathop \rightleftharpoons \limits^{K_{ex} } LnL_{3(O)} + 3H^ + + mH_2 O(Ln^{3 + } = Yb,Lu),$$ two-phase stability constants for theLnL ₃ complexes,pH _0.5 and the separation factor Lu(III) from Yb(III).     

Americium(III) coordination chemistry: An unexplored diversity of structure and bonding

The comparison of the physicochemical behavior of the actinides with that of the lanthanides can be justified by the analogy of their electronic structure, as each of the series is made up of elements corresponding to the filling of a given (n)f atomic shell. However relatively few points of comparison are available, given the lack of available structure for trans-plutonium(III) elements and the additional difficulty of stabilizing coordination complexes of uranium(III) to plutonium(III). This contribution is a focal point of trans-plutonium(III) chemistry and, more specifically, of some americium compounds that have been recently synthesized, all related with hard acid oxygen donor ligands that may be involved in the reprocessing chain of nuclear fuel. After a brief review of the solid hydrates and aquo species for the lanthanide and actinide families, we discuss two types of ligands that have in common three carboxylic goups, namely the aminotriacetic acid and the citric acid anions. The additional roles of the nitrogen atom for the first one and of the hydroxy function for the second one are discussed. Accordingly, five new complexes with either americium or lanthanides elements are described: [Co(NH₃)₆][M(NTA)₂(H₂O)]·8H₂O with M = Nd, Yb and Am, and [Co(NH₃)₆]₂K[M₃(Cit)₄(H₂O)₃]·18H₂O with Nd and Am cations. In all cases the americium complexes are isostructural with their lanthanide equivalents.     

Thermal decomposition of lanthanide(III) complexes of bis-(salicylaldehyde)-1,3-propylenediimine Schiff base ligand

The thermal decomposition of lanthanide complexes, with a general formula: [LnL(NO₃)₂](NO₃), where Ln = La, Pr, Nd, Sm, Gd, Tb, Dy, and Er; and L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand, was studied by thermogravimetric (TG) and derivative thermogravimetric (DTG) techniques. The TG and DTG data indicated that all complexes are thermostable up to 398 K. The thermal decomposition of all Ln(III) complexes was a two-stage process and the final residues were Ln₂O₃ (Ln = La, Nd, Sm, Gd, Dy, Er), Tb₄O₇, and Pr₆ O₁₁. The activation energies of thermal decomposition of the complexes were calculated from analysis of the TG-DTG curves using the Kissinger, Friedman, and Flynn-Well-Ozawa methods.     

Synthesis and characterization of novel heteronuclear complexes of Ln(III)-Cu(II) with non-cyclic polyether Schiff base

Nine novel heteronuclear complexes of Ln(III)-Cu(II) with salicylidene tetraethylene glycol diamine (SALTTA) have been synthesized and characterized. They have the general formulae [L_nC_u2(SALTTA)₂(NO₃)₃](NO₃)₄·3H₂O (Ln=La, Pr, Nd, Sm) and [LnCu₃(SALTTA)₃(NO₃)₅]-(NO₃)₄·4H₂O (Ln=Gd, Tb, Er, Yb, Y). The IR spectra show that v_C=N in the Ln(III)-Cu(II) heteronuclear complexes are splitted up into two peaks with a far distance. It has been confirmed that oxygen atoms in oxyethylene of the ligand are not all coordinated to the central metal ions by both IR and NMR methods.