- Reduced lanthanum halides with Ge as interstitials: La2I 2Ge, La2I2Ge2, La3Cl 2Ge3, La3Br2Ge3, La 3I3Ge, La
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The title compounds were synthesized from La, LaX3 (X = Cl, Br and I) and Ge under Ar atmosphere at temperatures 860-1200°C. Their structures are characterized by Ge-centered La6 octahedra or trigonal prisms. Ge atoms form planar zig
- Mattausch, Hansjuergen,Zheng, Chong,Ryazanov, Mikhail,Simon, Arndt
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- 1D-Polyoxometalate-Based Composite Compounds - Design, Synthesis, Crystal Structures, and Properties of [{Ln(NMP)6}(PMo12O 40)]n (Ln = La, Ce, Pr; NMP = N-methyl-2-pyrrolidone)
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The structures of three 1:1 composite compounds prepared with the polyoxometalate (POM) [PMo12O40]3- and the cations [Ln(NMP)6]3+ [Ln = La (1), Ce (3), Pr (2); NMP = N-methyl-2-pyrrolidone] exhibit two types of zig-zag chains with alternating cations and anions through Mo-Ot-Ln-Ot-Mo links in the crystal. The compounds were characterized by IR, UV, and ESR spectroscopy, single-crystal X-ray structural analysis, and by a study of their thermal properties. In all the compounds, the La3+, Pr3+, and Ce3+ centers are eight-coordinate with the oxygen atoms in bicapped trigonal-prismatic geometries. The variation of the average Ln-O separations along the La, Ce, and Pr series is consistent with the effects of the lanthanide contraction. The results of the single-crystal X-ray diffraction analyses and the IR spectroscopic studies are in agreement and both show the metal cation units are coordinatively bonded to the Keggin clusters. The UV spectra of the title compounds suggest that their structures are entirely disrupted in dilute solution. Low-temperature ESR spectra indicate that thermal electron delocalization occurs among the Mo atoms in the three compounds. The results of cyclic voltammetry (CV) show that compounds 1, 2, and 3 all undergo five two-electron reversible reductions and that the [PMo12O 40]3- anions are the active centers for electrochemical redox reactions in solution, while the corresponding cations have only a small effect on the electrochemical properties. Studies of magnetic properties show that 1 is diamagnetic, while 2 and 3 exhibit antiferromagnetic Pr-Pr or Ce-Ce exchange interactions. In addition to the results of CV, the average bond lengths and the magnetic properties of compound 3 indicate that the oxidation state of cerium is iii in the compound of formula [{Ce(NMP) 6}(PMo12O40)]n. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Niu, Jing-Yang,Wei, Mei-Lin,Wang, Jing-Ping,Dang, Dong-Bin
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- Gelation of La(III) cations promoted by 5-(2-pyridyl)tetrazolate and water
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Addition of water to the product formed when LaCl3 and 1H-5-(2-pyridyl)tetrazole (LH) were treated with an excess of triethylamine in ethanol, resulted in the reversible formation of a hydrogel, which when further treated with EtOH-iPrOH produced crystals of [LaL3(H 2O)3]·(H2O)4, as determined by X-ray crystallography. The Royal Society of Chemistry 2006.
- Andrews, Philip C.,Junk, Peter C.,Massi, Massimiliano,Silberstein, Morry
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- Synthesis and structure of the new compound La2O(CN 2)2 possessing an interchanged anion proportion compared to the parent La2O2(CN2)
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La2O(CN2)2 was synthesized from a 1:1:2 molar reaction mixture of LaCl3, LaOCl, and Li2(CN 2) at 650°C. Well developed single crystals were grown from a LiCl-KCl flux. The crystal structure was refined as monoclinic (space group C2/c, Z = 2, a = 13.530(2) A, b = 6.250(1) A, c = 6.1017(9) A, β = 104.81(2)°) from single crystal X-ray diffraction data. The La3+ and (CN2)2- ions in the crystal structure of La2O(CN2)2 can be compared to Fe 3+ and S22- ions in the cubic pyrite structure, being arranged like in a distorted NaCl type structure with their centers of gravity. In addition, the O2- ions in La2O(CN 2)2 are occupying 1/4 of the tetrahedral voids formed by the arrangement of metal ions.
- Srinivasan, Radhakrishnan,Tragl, Sonja,Meyer, H.-Juergen
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- Catalytic hydrogen-chlorine exchange between chlorinated hydrocarbons under oxygen-free conditions
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(Figure Presented) Pass the parcel: Activity experiments show that LaCl3 supported on carbon nanofibers is a highly active, selective, and stable catalyst for the H-Cl exchange reaction between CCl4 and CH2Cl2 to form CHCl3 (see scheme) in the absence of either lattice or gas-phase oxygen. Density functional calculations suggest that the reaction proceeds through the formation of weakly adsorbed Cl and H species which can be exchanged between the reactants.
- Van Der Heijden, Alwies W. A. M.,Podkolzin, Simon G.,Jones, Mark E.,Bitter, Johannes H.,Weckhuysen, Bert M.
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- Destabilization of LiBH4 by (Ce, La)(Cl, F)3 for hydrogen storage
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The mixtures of LiBH4 with halides of Ce or La in a molar ratio of 3:1 were investigated to explore their hydrogen storage properties. The ball milling of LiBH4 with chloride of Ce or La yielded Ce(BH 4)3 and La(BH4)3, while fluoride of Ce or La did not react with LiBH4 during extended ball milling at room temperature. The dehydrogenation temperatures of the ball-milled mixtures were reduced to 220-320 °C, which were much lower than that of pure LiBH4. The diborane emission during hydrogen release was observed at a low level. The dehydrogenation temperature is found to be affected by the composition of rare earth halides, but less influenced by ball milling time. The endothermic dehydrogenation reactions produced lithium halides, hydrides and borides of the corresponding rare earth element. Moreover, the LiBH4 + 1/3(Ce, La)(Cl, F)3 showed partial reversibility through the formation of an unknown borohydride, allowing for a potential hydrogen storage system.
- Zhang, Bang Jie,Liu, Bin Hong,Li, Zhou Peng
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- Study of the chemical chelates and anti-microbial effect of some metal ions in nanostructural form on the efficiency of antibiotic therapy norfloxacin drug
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This paper has reviewed the chemical and biological impact resulting from the interaction between norfloxacin (norH) antibiotic drug and two lanthanide (lanthanum(III) and cerium(III)) metal ions, which prepared in normal and nano-features. La(III) and Ce(III) complexes were synthesized with chemical formulas [La(nor)3]·3H2O and [Ce(nor) 3]·2H2O. Lanthanum and cerium(III) ions coordinated toward norH with a hexadentate geometry. The norH acts as deprotonated bidentate ligand through the oxygen atom of carbonyl group and the oxygen atom of carboxylic group. Elemental analysis, FT-IR spectral, electrical conductivity, thermal analysis (TG/DTA), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) measurements have been used to characterize the mentioned isolated complexes. The Coats-Redfern and Horowitz-Metzger integral methods are used to estimate the kinetic parameters for the major successive steps detectable in the TG curve. The brightness side in this study is to take advantage for the preparation and characterization of single phases of La2O3 and CeO2 nanoparticles using urea as precursors via a solid-state decomposition procedure. The norH ligand in comparison with both cases (normal and nano-particles) of lanthanide complexes were screened against for antibacterial (Escherichia Coli, Staphylococcus Aureus, Bacillus subtilis and Pseudomonas aeruginosa) and antifungal (Aspergillus Flavus and Candida Albicans) activities. The highest antibacterial and antifungal activities data of the nano-particles complexes were observed with more potent than the free norH and normal lanthanide complexes.
- Refat, Moamen S.,El-Hawary,Mohamed, Mahmoud A.
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- Rare earth halides Ln4X5Z. Part 3: The chloride La4Cl5B4 - Preparation, structure, and relation to La4Br5B4, La4I5B 4
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La4Cl5B4 is synthesized by reaction of LaCl3, La metal and boron in sealed Ta containers at 1050 °C a = 16.484(3) A, b = 4.263(1) A, c = 9.276(2) A and β = 120.06(3)°. Ce4Cl5B4 is isotypic, a = 16.391(3) A, b = 4.251(1) A, c = 9.180(2) A and β = 120.20(3)°. The La atoms form strings of trans-edge shared La octahedra, and the B atoms inside the strings form B4-rhomboids, which are condensed to chains via opposite corners. The Cl atoms interconnect the channels according to La2La4/2Cli-i 6/2Cli-a 2/2Cla-i2/2. The crystal structures of the bromide and the iodide are comparabel, however, the interconnection of the strings is different in the three structure types, as 14 Cl, 13 Br and 12 I atoms surround the La6 octahedra.
- Mattausch, Hansjuergen,Oeckler, Oliver,Simon, Arndt
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- Lanthanum phosphite microspheres: Hydrothermal synthesis, ab initio structure determination, morphology and photoluminescence of La(HO)(HPO 3)
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Lanthanum phosphite microspheres with diameters of 80100 μm were obtained under hydrothermal conditions by using lanthanum oxalate as precursor, The surfaces of these spherules consist of well-orientated submicron-sized rods with typical diameters of 300
- Xiong, Ding-Bang,Zhao, Yu-Feng,Gulay, Lubomir D.,Zhao, Jing-Tai
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- Lanthanum(III) chloride complexes with heterocyclic Schiff bases : SSynthesis, spectroscopic characterization and thermal studies
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Condensation of 2-amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene with carbonyl compounds such as isatin, o-hydroxyacetophenone or benzoin in 1:1 ratio in ethanol medium yielded three distinctly different heterocyclic Schiff bases viz. 2-(N-indol
- Thankamony,Sindhu Kumari,Mohanan,Rijulal
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- Luminescence and structural properties of lanthanide complexes of Schiff bases derived from pyridoxal and amino acids
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Lanthanide complexes of Schiff bases (SBs) with 1: 1 and 1: 2 (M: Lig) stoichiometric ratios were prepared by condensation of pyridoxal (PL) and aspartic acid (Asp) or l-histidine (His), respectively, in the presence of the appropriate metal chloride as a templating agent. These complexes were studied by optical spectroscopy and single crystal X-ray diffraction techniques. Crystallographic studies of 1: 1 ([Eu(PL-Asp)(H2O) 4](H2O)) and 1: 2 ([Eu(PL-His)2(H 2O)2]Cl(H2O)4) complexes show that EuIII is eight-coordinate in both structures, in a distorted square antiprism environment formed by the phenolic oxygen of PL, the nitrogen atom of carbon-nitrogen double bond, oxygen atoms of the carboxylate groups of His or Asp, and oxygen atoms of the water molecules. The main species formed in aqueous solutions containing these SBs have been determined by analysis of the luminescence spectra, lifetimes of EuIII excited states and vibronic interaction as well as structural features of the EuIII coordination sphere. Possible tetradentate coordination function of SBs in aqueous solutions with relatively high concentrations as well as the potential application of the lanthanide SB complexes as new luminescence materials are discussed. The Royal Society of Chemistry.
- Puntus, Lada,Zhuravlev, Konstantin,Lyssenko, Konstantin,Antipin, Mikhail,Pekareva, Irina
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- Kinetics and mechanism of the thermal decomposition of lanthanum complexes of 4-N-(4'-antipyrylmethylidene) aminoantipyrine
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The kinetics and mechanism of the thermal decomposition of perchlorate, nitrate, chloride, bromide, and iodide complexes of lanthanum with the Schiff base 4-N-(4'-antipyrylmethylidene) aminoantipyrine (abbreviated asAA) have been studied by TG and DTG tec
- Nair, M. K. Muraleedharan,Radhakrishnan, P. K.
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- Bridgman growth of LaCl3:Ce3+ crystal in non-vacuum atmosphere
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Growth of LaCl3:Ce3+ crystal by the vertical Bridgman process in non-vacuum atmosphere has been studied. Based on the dehydration procedure of LaCl3·7H2O and CeCl3·7H2O investigated by DTA/TG, anhydrous LaCl3 and CeCl3 were prepared by heating LaCl3·7H2O and CeCl3·7H2O at 200-230 °C for 6-7 h in dried HCl atmosphere. Using the feed materials prepared from the anhydrous lanthanon chlorides, a 4 mol% Ce3+ doped LaCl3 crystal with a size of ? 28 mm × 70 mm was successfully grown. The crystal was grown under the optimum conditions such as a growth rate of 0.5-0.8 mm/h and a temperature gradient of around 30 °C/cm across solid-liquid interface at a furnace temperature of 940-960 °C. The Bridgman process is confirmed to be promising for growing large size LaCl3:Ce3+ crystals with high quality.
- Chen, Hongbing,Yang, Peizhi,Zhou, Changyong,Jiang, Chengyong
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- Thermal decomposition kinetics of lanthanum complexes of 1,2-(diimino-4′-antipyrinyl)ethane
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The kinetics and mechanism of the thermal decomposition of perchlorate, nitrate and iodide complexes of lanthanum with the Schiff base 1,2-(diimino-4′-antipyrinyl)ethane (abbreviated as GA) have been studied by TG and DTG techniques. The kinetic parameter
- Nair,Radhakrishnan
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- Layered lanthanum carbide halide superconductors La2C2(X,X′)2 (X,X′ = Cl, Br, I): Neutron powder diffraction characterization and electronic properties
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The superconducting properties of La2C2(X, X′)2(X, X′ = Cl, Br, I) are investigated. Three different samples of La2C2Br2, which are obtained under different synthesis conditions, show superconductivity at 7.03(5) K. La2C2I2 (Tc≈1.7 K) exhibits slightly different transition temperatures for differently prepared samples. A total of five samples of La2C2(X, X′)2 were investigated by high resolution neutron powder diffraction from room temperature to 1.5 K. Rietveld refinements yield the structural parameters, in particular of the C atoms. These allow us to follow in detail the variation of the interatomic distance in the C2 group. On the basis of the low temperature structural parameters, extended Hueckel band structure calculations were performed and a band of low dispersion along the Γ-N direction in the Brillouin zone was identified. We discuss correlations of structural and electronic properties with the superconducting transition temperatures of the La2C2(X, X′)2 phases.
- Ahn, Kyungsoo,Gibson, Brendan J.,Kremer, Reinhard K.,Mattausch, Hansjuergen,Stolovits, Andres,Simon, Arndt
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- Molecular nitrides with titanium and rare-earth metals
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A series of titanium-group 3/lanthanide metal complexes have been prepared by reaction of [{Ti(η5-C5Me5)(μ-NH)} 3(μ3-N)] (1) with halide, triflate, or amido derivatives of the rare-earth metals. Treatment of 1 with metal halide complexes [MCl3(thf)n] or metal trifluoromethanesulfonate derivatives [M(O3SCF3)3] at room temperature affords the cube-type adducts [X3M{(μ3-NH) 3Ti3(η5-C5Me5) 3(μ3-N)}] (X = Cl, M = Sc (2), Y (3), La (4), Sm (5), Er (6), Lu (7); X = OTf, M = Y (8), Sm (9), Er (10)). Treatment of yttrium (3) and lanthanum (4) halide complexes with 3 equiv of lithium 2,6-dimethylphenoxido [LiOAr] produces the aryloxido complexes [(ArO)3M{(μ3- NH)3Ti3(η5-C5Me 5)3(μ3-N)}] (M = Y (11), La (12)). Complex 1 reacts with 0.5 equiv of rare-earth bis(trimethylsilyl)amido derivatives [M{N(SiMe3)2}3] in toluene at 85-180 °C to afford the corner-shared double-cube nitrido compounds [M(μ3-N) 3(μ3-NH)3{Ti3(η5- C5Me5)3(μ3-N)}2] (M = Sc (13), Y (14), La (15), Sm (16), Eu (17), Er (18), Lu (19)) via NH(SiMe 3)2 elimination. A single-cube intermediate [{(Me 3Si)2N}Sc{(μ3-N)2(μ 3-NH)Ti3(η5-C5Me 5)3(μ3-N)}] (20) was obtained by the treatment of 1 with 1 equiv of the scandium bis(trimethylsilyl)amido derivative [Sc{N(SiMe3)2}3]. The X-ray crystal structures of 2, 7, 11, 14, 15, and 19 have been determined. The thermal decomposition in the solid state of double-cube nitrido complexes 14, 15, and 18 has been investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) measurements, as well as by pyrolysis experiments at 1100 °C under different atmospheres (Ar, H2/N2, NH3) for the yttrium complex 14.
- Caballo, Jorge,Garcia-Castro, Maria,Martin, Avelino,Mena, Miguel,Perez-Redondo, Adrian,Yelamos, Carlos
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- Synthesis, characterization, and reactivity of ansα-Bis(allyl) Lanthanide complexes, a new class of single-component methyl methacrylate polymerization catalysts
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The reaction of the dipotassium salt K2{3-(C3H 3SiMe3-1)2SiMe2} with LnCl 3 in THF leads to the formation of the new ansa-allyl lanthanate complexes [Ln{(η3-C3H3SiMe 3)2SiMe2} 2{μ-K(THF)} ·nTHF]∞ (1, Ln = La, n = 0.5; 2, Ln = Y, n = 1; 3, Ln = Sc, n = 1). Reaction of K2{3-(C3H 3SiMe 3-1)2SiMe2} with NdI 3(THF) 3.5 affords THF-free [Nd{η3-C 3H 3SiMe3)2SiMe2} 2(μ-K)] ∞ (4). Treatment of SmI2(THF)2 with Li{3-(C 3H3SiMe3-1)2SiMe 2}/KOtBu resulted in the samarium(III) complex [Li(OEt2)4][Sm{(η3-C3H 3SiMe3)2SiMe2}2] (5), albeit in small yield. Whereas the crystal structure of 1 shows a coordination polymer, with potassium bridging to allyl moieties of two neighboring lanthanide units and close K...CH3Si contacts, complex 5 consists of discrete ions. The complexes 1-5 are all found to be efficient catalysts for the polymerization of methyl methacrylate to high-molecular-weight polymers under a variety of conditions, with 2 at 0 °C giving extremely high turnovers of 86 400 mol of MMA (mol of Y) -1 h-1.
- Woodman, Timothy J.,Schormann, Mark,Bochmann, Manfred
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- Description and Structure of New Compounds Ln//3MO//5XCl//3 (Ln EQUVLNT La, Ce, Pr, Nd, Th; M EQUVLNT Ta, Nb; X EQUVLNT O, OH, F).
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La//2ThTaO//6Cl//3, a representative of a group of isostructural Ln//3MO//5XCl//3-type compounds with Ln EQUVLNT La - Nd, Th, X EQUVLNT O, OH, F and M EQUVLNT Ta, Nb, crystallizes in the hexagonal space group P6//3/m. The compound was prepared by the interaction of ThO//2, LaTaO//4 and LaCl//3. Single crystals were obtained by chemical transport reactions (1080 yields 940 degree C) using chlorine as the transport agent. The structure consists of TaO//6 polyhedra with an unusual trigonally prismatic environment for the Ta. La and Th are randomly distributed over the 6(h) sites with a coordination number CN equals 10.
- Schaffrath, U.,Gruehn, R.
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- A cluster with a mixed M6X12/M6X8 environment: The La6Cl11Co structure
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The title compound was synthesized from La, LaCl3 and Co under Ar atmosphere at 800 °C. It crystallizes in space group P42/n (no. 86) with lattice constants a=11.308(2) A and c=14.441(3) A. The structure features an isolated Co-cente
- Zheng, Chong,Mattausch, Hansjuergen,Hoch, Constantin,Simon, Arndt
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- Chlorination of lanthanum oxide
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The reactive system La2O3(s)-Cl2(g) was studied in the temperature range 260-950 °C. The reaction course was followed by thermogravimetry, and the solids involved were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the reaction leads to the formation of solid LaOCl, and for temperatures above 850 °C, the lanthanum oxychloride is chlorinated, producing LaCl3(l). The formation of the oxychloride progresses through a nucleation and growth mechanism, and the kinetic analysis showed that at temperatures below 325 °C the system is under chemical control. The influence of diffusive processes on the kinetics of production of LaOCl was evaluated by studying the effect of the reactive gas flow rate, the mass of the sample, and the chlorine diffusion through the boundary layer surrounding the solid sample. The conversion curves were analyzed and fitted according to the Johnson-Mehl-Avrami description, and the reaction order with respect to the chlorine partial pressure was obtained by varying this partial pressure between 10 and 70 kPa. The rate equation was obtained, which includes the influence of the temperature, chlorine partial pressure, and reaction degree.
- Gaviria, Juan P.,Navarro, Lucas G.,Bohe, Ana E.
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- MOF formation vs. reversible high ligand uptake in anhydrous halides: Two opposing aspects of ∞3 [La2CI6(4,4'-bipy) 5]·4(4,4'-bipy)
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Construction of the framework, structure ∞3 (bipy)5]· 4bipy (1), bipy = 4,4'-bipyridine, C10H 8N2, is achieved by reaction of the anhydrous halide LaCl3 with molten 4,4'-bipyridine. Five equivalents of bipyridine are used for the framework construction linking LaCl3 units to give an extended, three-dimensional MOF. Furthermore, four additional equivalents of bipyridine per LaCl3 unit are incorporated within the crystalline MOF, which is thereby completely filled with bipy molecules. This compound formation results in the extraordi-nary high uptake of nine equivalents of bipyridine per equivalent of the formula and a volume increase of eight times the volume of LaCl3. Further heating of the MOFs results in a stepwise release of all nine equivalents of bipyridine and reformation of the anhydrous chloride at 425 °C. Formation and disassembly can be run in cycles and are reversible. Thus two interesting yet opposing aspects are the reversible construction and disassembly of the MOF framework.
- Hoeller, Christoph J.,Matthes, Philipp,Beckmann, Jens,Mueller-Buschbaum, Klaus
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- Microstructure and desorption properties study of catalyzed NaAlH 4
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NaAlH4 catalyzed by Ce(SO4)2 and LaCl 3 have been studied by PCT (Pressure-Content-Temperature) experiment and SEM (Scanning Electron Microscope) test method. The results show that doping with Ce(SO4)2 and LaCl3 increases markedly the desorption amount of NaAlH4. In the first desorption stage, NaAlH4 doped with LaCl3 display larger amount of hydrogen release than NaAlH4 doped with Ce(SO4)2, while, the desorption rate of the latter is obviously faster than the former. SEM analysis shows that heating could make NaAlH4 form a kind of porous structure. The further study indicates that different dopants have different effects on the microstructure of NaAlH4.
- Xueping, Zheng,Xin, Feng,Shenglin, Liu
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- Electrodeposition of RE-TM (RE = La, Sm, Gd; TM = Fe, Co, Ni) films and magnetic properties in urea melt
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Rare earth (RE)-3d transition metal (TM) films were codeposited in low temperature urea-acetamide-NaBr-KBr-RECl3-TMCl2 baths by potentiostatic electrolysis. Cyclic voltammetry is used to investigate the electrochemical behavior of RE
- Li, Jiaxin,Lai, Heng,Fan, Biqiang,Zhuang, Bin,Guan, Lunhui,Huang, Zhigao
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- Electro-deposition of Co-La alloy films in urea melt and their performances
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The Co-La alloy film was electro-deposited in urea melt. The co-deposition behavior, the effect of the cathodic current density on the composition and the surface morphology of the coating were examined, respectively. As a result, lanthanum is co-deposited with cobalt to form Co-La alloy under the inducement effect of cobalt. With the increase of the cathodic current density, La content of the deposit rises at first, then decreases, and reaches a maximal value at the current density of 30 mA cm-2. Meanwhile, the size of the coating particles becomes small. The more content of Co in the deposit is, the more the saturation magnetization is. The crystallization behavior of the coating was studied by using the differential scanning calorimetry and the X-ray diffraction. The as-plated deposit consists of main amorphous phase and a little amount of hexagon cobalt phase (P63/mmc). The amorphous phase was converted into Co-La (Fm3m) phase at 438.9 °C, and hexagon cobalt phase was crystallized into cubic cobalt at 687.1 °C. The electro-catalytic activity of the hydrogen evolution for the Co-La alloy was studied by using electrochemical experiments. The results showed that the electro-catalytic activity of the hydrogen evolution of the alloy is better than that of cobalt.
- Wang, Sen-Lin,Lin, Ji-Bei,Cai, Qiu-Yan,Zhang, Yan
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- Two structurally related oxide nitride chalcogenides of the lanthanoids: Tb3ONSe2 and la5O2NS4
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The structurally related oxide nitride chalcogenides Tb 3ONSe2 and La5O2NS4 can be prepared by the oxidation of the respective lanthanoid metal (M = Tb and La) with selenium or sulfur and sodium azide (NaN3) in the presence of oxygen-containing impurities, when iodine (I2) or the corresponding lanthanoid trichloride (MCl3) is used as sodium trap for the formation of NaI or NaCl, respectively. The thermal treatment of these mixtures along with additional Nal or NaCl as flux at 900 °C in evacuated silica tubes yielded transparent, yellow polyhedra in the case of Tb 3ONSe2 or orange, lathshaped crystals of La 5O2NS4. Both monoclinic structures (C2/m, Z = 4) were determined from X-ray single-crystal diffraction data (Tb 3ONSe2: a = 1548.85(9), b = 392.02(2), c = 968.61(6) pm, ss = 97.194(3)°; La5O2NS4: a = 1571.13(8), b = 409.67(2), c = 1681.03(9) pm, ss = 101.204(3)°). The crystal structure of Tb3ONSe2 comprises three crystallographically different Tb3+ cations residing in six- and sevenfold coordination of the respective anions, whereas the crystal structure of La5O2NS4 shows five different La 3+ cations with coordination numbers from six to eight. For the first time in the chemistry of oxide nitride chalcogenides of the lanthanides, an ordering of the light anions (O2- and N3-) is observed, and proper structure descriptions based on vertex- and edge-connected [OM 4]10+ and [NM4]9+ tetrahedra (M= Tb and La) becomes possible. As main structural feature, a bulky chain 1 ∞ {[ONTb3]4-} running along [010] can be detected in the crystal structure of Tb3ONSe2. The same morphology, but a different chemistry is realized in the related crystal structure of La5O2NS4, where these topological equivalent strands 1 ∞{[O2La 3]5+} and an additional second chain 1 ∞{[NLa2J3+}, built up by vertex- and edge connected [NLa4]9+ tetrahedra, compose the compound. As supporting tool for the distinction of the O2- and N3- anions in both crystal structures, the valence-bond concept is also applied.
- Lissner, Falk,Strobel, Sabine,Schleid, Thomas
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- La3Cl3BC - Structure, bonding and electrical conductivity
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A new rare earth carbide boride halide, La3Cl3BC, has been prepared by heating a mixture of stoichiometric quantities of LaCl 3, La, B and C at 1050°C for 10 days. La3Cl 3BC (La3Br3BC type) crystallizes in the monoclinic system with space group P21/m (No. 11), a = 8.2040(16), b = 3.8824(8), c = 11.328(2) A?, β = 100.82(3)°. In the structure, monocapped trigonal prisms containing B-C units are condensed into chains along the b direction, and the chains are further linked by Cl atoms in the a and c directions. The condensation results in a polymeric anion ∞1[BC] with a spine of B atoms in a trigonal prismatic coordination by La, and the C atoms attached in a square pyramidal coordination. The B-B and B-C distances are 2.16 and 1.63 A?, respectively. La3Cl3BC is metallic. The EH calculation shows that the distribution of valence electrons can be formulated as (La3+) 3(Cl-)3(BC)5-·e-.
- Zeng, Hui-Yi,Okudera, Hiroki,Zheng, Chong,Mattausch, Hansjürgen,Kremer, Reinhard K.,Simon, Arndt
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- Zintl anions of silicon in the halides La3Cl2Si3 and La6Br3Si7
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La3Cl2Si3 and La6Br3Si7 are prepared at temperatures of around 950 °C from LaX3 (X = Cl, Br), La metal and Si as starting materials. La3Cl2Si3 crystallizes in C2/m with a = 1802(3), b = 420.6(4), c = 1058(2) pm, β= 97.9(2)°, and La6Br3Si7 in Pmmn mit a = 1686.9(2), b = 412.93(11), c = 1185.2(1) pm. In both compounds the Si atoms are located in trigonal prisms of La atoms, which are connected through common triangular and rectangular faces to form layers. The bromine atoms connect the metal atom double layers. In La3Cl2Si3 the Si atoms form zig-zag chains, in La6Br3Si7 chains build up from 1∞-connected Si12 rings. Both compounds are metallic conductors.
- Mattausch, Hansjuergen,Oeckler, Oliver,Simon, Arndt
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- Local structure of molten LaCl3 analyzed by X-ray diffraction and La-LIII absorption-edge XAFS technique
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From the radial distribution analysis of X-ray diffraction, the nearest neighbor La-Cl distance and coordination number of Cl around La in molten LaCl3 were estimated to be about 0.28 nm and nearly equal to 6, respectively. On the other hand, according to the XAFS measurements, the coordination number of Cl around La was evaluated at about 7. As a result, the local structure of molten LaCl3 was thought to be described as an octahedral-like coordination scheme where La was surrounded by about six or seven Cl's. This finding led to the formation of octahedral complex ion, LaCl63-, which was in agreement with results of Raman spectroscopy by other authors. The La-La distance was evaluated at about 0.5 nm from the position of a weak and broad second peak in the correlation function g(r), suggesting that a distorted corner-sharing connection of two octahedral complex species was predominant in the melt.
- Iwadate,Suzuki,Onda,Fukushima,Watanabe,Matsuura,Kajinami,Takase,Ohtori,Umesaki,Kofuji,Myochin
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- High-temperature infrared spectroscopy of YCl3: the vibration spectrum, molecular structure and thermodynamic functions
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The infrared spectrum of gaseous YCl3 has been measured at 1400 K and three absorption bands have been found in the 50-600 cm-1 range.Based on a comparison with LaCl3, of which the spectrum was also recorded, it is concluded that the absorption maximum at 370 cm-1 is an overlap of the two stretching frequencies of a pyramidal structure.By spectral deconvolution, the absorption bands could be separated, resulting in the following vibrational assignments: ν1 = 378; ν2 = 78; ν3 = 359; ν4 = 58.6 cm-1.From these data the ideal gas thermodynamic functions have been calculated.
- Konings, R. J. M.,Booij, A. S.
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- Sheets of La6(C2) octahedra in lanthanum carbide chlorides - Undulated and plane
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The reaction of Ln, LnCl3 (Ln = La, Ce) and C yields the hitherto unknown compounds La8(C2)4Cl 5, Ce8(C2)4Cl5, La 14(C2)7Cl9, La20(C 2)10Cl13, La22(C2) 11Cl14, La36(C2)18Cl 23 and La2(C2)Cl. The gold- resp. bronze-coloured metallic compounds are sensitive to moisture. The reaction temperatures are 1030°C, 1000°C, 970°C, 1020°C, 1020°C, 1080°C and 1030°C in the order of compounds given, which mostly crystallize in the monoclinic space group P21/c with a = 7.756(1) A, b = 16.951(1) A, c = 6.878(1) A, β = 104.20(1)° (La8(C2)4Cl5), a = 7.669(2) A, b = 16.784(3) A, c = 6.798(1) A, β = 104.05(1)° (Ce 8(C2)4Cl5), a = 7.669(2) A, b = 16.784(3) A, c = 6.789(1) A, β = 104.05(3)° (La 20(C2)10Cl13), a = 7.770(2) A, b = 47.038(9) A, c = 6.901(1) A, β = 104.28(3)° (La 22(C2)11Cl14) and a = 7.764(2) A, b = 77.055(15) A, c = 6.897(1) A, β = 104.26(3)° (La36(C2)18Cl23), respectively. La14(C2)7Cl9-(II) crystallizes in Pc with a = 7.775(2) A, b = 29.963(6) A, c = 6.895(1) A, β = 104.21(3)° and La2(C2)Cl in C2/c with a = 14.770(2) A, b = 4.187(1) A, c = 6.802(1) A, β = 101.50(3)°. The crystal structures are composed of distorted C2 centered La-octahedra which are condensed into chains via common edges. Three and four such chains join into ribbons, and these are connected into undulated layers with Cl atoms between them. The variations of the structure principle are analyzed systematically.
- Mattausch, Hansjuergen,Simon, Arndt,Kienle, Lorenz,Koehler, Juergen,Hoch, Constantin,Nuss, Juergen
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- Pulse current electrodeposition of Al from an AlCl3-EMIC ionic liquid
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Electrodeposition of aluminum from an AlCl3-EMIC ionic liquid with or without the addition of saturated LaCl3 was carried out by both direct- and pulse-current plating methods. The effects of various parameters, including current density, pulse frequency, current on/off duration (ton and toff), and temperature, on deposit morphology and crystal size were investigated. Deposits prepared by pulse-current plating gave a brighter and flatter surface than those prepared by direct-current plating at appropriate pulse current parameters. Temperature and pulse-current frequency (toff) were shown to significantly affect deposit morphology. Coalescence of grains during toff periods in the pulse current plating was observed, especially at temperatures above 60 °C. Increasing the temperature from 25 to 90 °C caused an increase in deposit grain size and resulted in a change of grain shapes from a small sphere-like form to a feather-like form. As a result, the adhesion of the deposited aluminum to the substrate was lowered. Smaller grain sizes and well-adhered deposits were achieved at lower temperatures. For example, deposition at 25 °C resulted in the smallest crystal size of about 0.3 μm under the conditions of t on = 80 ms, toff = 20 ms, and i = 8 mA/cm2. Furthermore, the addition of LaCl3 to the melt at 60 °C effectively reduced the porosity and improved compactness of deposits.
- Li, Bing,Fan, Chunhua,Chen, Yan,Lou, Jingwei,Yan, Lingguang
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- INTERNAL ROTATION AND PHASE TRANSITIONS IN LANTHANUM TETRAHYDROBORATES
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Usig the 1H, 11B, 139La NMR and relaxation MR methods, we have investigated the molecular dynamics in La(BH4)3 and its adduct with tetrahydrofuran La(BH3)3*3THF.We have observed phase transitions connected with the change in the nature of the internal rotation (reorientation) of the BH4- anions.We have determined the barrier to reorientation of the BH4- anions and the THF molecules in the investigated compounds, and we have shown that the change in the mobility of the THF molecule does not lead to a phase transition.
- Volkov, V. V.,Khikmatov, M.,Mirsaidov, U.,Gabuda, S. P.,Kozlova, S. G.
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- Luminescent properties of ytterbium-doped ternary lanthanum chloride
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Studies of the absorption and temperature dependence of photoluminescence spectra and luminescence decay times of the intra-shell f-f transitions ( 2F5/2 ? 2F7/2) of Yb 3+ ions in K2LaClsu
- Kaminska,Cybińska,Zhydachevskii,Sybilski,Meyer,Suchocki
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- Thermal and spectroscopic studies on solid Ketoprofen of lighter trivalent lanthanides
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Solid-state Ln(L)3 compounds, where Ln stands for trivalent La, Ce, Pr, Nd, Sm, Eu, and L is ketoprofen have been synthesized. Thermogravimetry (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC) as well as X-ray diffraction powder (DRX) patterns, Fourier transformed infrared spectroscopy (FTIR), and other methods ofanalysis were used to study solid Ketoprofen of lighter trivalent lanth anides. The results provided information of the composition, dehydration, coordination mode, structure, thermal behavior, and thermal decomposition. The theoretical and experimental spectroscopic study suggests that the carboxylate group of ketoprofen is coordinate to metals as bidentatebond.
- Galico, D. A.,Holanda, B. B.,Perpetuo, G. L.,Schnitzler, E.,Treu-Filho, O.,Bannach, G.
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p. 371 - 380
(2012/04/23)
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- Synthesis, thermal properties and spectroscopic study of solid mandelate of light trivalent lanthanides
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Characterization, thermal stability and thermal decomposition of light trivalent lanthanide mandelates Ln(C6H5CH(OH)CO 2)3·nH2O (Ln = La to Gd, except Pm) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), experimental and theoretical infrared spectroscopy, elemental analysis, X-ray diffractometry, complexometry and TG-DSC coupled to FTIR. The dehydration of the lanthanum, samarium, europium and gadolinium compounds occurs in a single step while for praseodymium and neodymium ones it occurs in two consecutive steps. The thermal decomposition of the anhydrous compounds occurs in three, four or five consecutive steps, with formation of the respective oxides CeO2, Pr6O11 and Ln2O3 (Ln = La, Nd to Gd) as final residues. The results also provide information concerning the composition, thermal behavior and gaseous products evolved during the thermal decomposition of these compounds. The theoretical and experimental spectroscopic data suggest the possible modes of coordination of the ligand with the lanthanum.
- Gigante,Gomes,Lima,Caires,Treu-Filho,Ionashiro
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- Preparation and characterization of rare earth orthoborates, LnBO 3 (Ln = Tb, La, Pr, Nd, Sm, Eu, Gd, Dy, Y) and LaBO3:Gd, Tb, Eu by metathesis reaction: ESR of LaBO3:Gd and luminescence of LaBO3:Tb, Eu
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Lanthanide orthoborates of composition LnBO3 (Ln = Tb, La, Pr, Nd, Sm, Eu, Gd, Dy, Y) and LaBO3:Gd, Tb, Eu have been prepared by metathesis reaction. This method provides a convenient route for the synthesis of orthoborates and its solid solutions at low temperatures. Powder X-ray diffraction and FT-IR spectroscopy were used to characterize these borates. Rare earth borates, (LnBO3) are isomorphous with different forms of CaCO3 depending on the radius of rare earth ion. LaBO3, LaBO3:Gd, Tb, Eu, PrBO3, NdBO3 crystallized in aragonite structure, SmBO3 crystallized in H-form and TbBO 3, EuBO3, GdBO3, DyBO3, YBO 3 crystallized in vaterite structure. The structural analysis of TbBO3 was carried out. The morphology of these borates was obtained from Scanning electron microscopy. Spin-Hamiltonian parameters for Gd 3+ are deduced from room temperature electron spin resonance spectrum of LaBO3:Gd. The luminescence of LaBO3:Tb, Eu gave characteristics peaks corresponding to Tb3+, Eu3+ respectively.
- Velchuri, Radha,Kumar, B. Vijaya,Devi, V. Rama,Prasad,Prakash, D. Jaya,Vithal
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p. 1219 - 1226
(2011/07/09)
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- Synthesis, characterization and thermal behaviour of light trivalent lanthanides folates on solid state
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Solid state Ln2-L3 compounds, where Ln stands for light trivalent lanthanides (lanthanum to gadolinium), except promethium, and L is folate (C19H17N7O6), have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy (FTIR), TG coupled to FTIR, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results provided information concerning the stoichiometry, crystallinity, ligand's denticity, thermal stability, thermal behaviour and identification of the gaseous products evolved during the thermal decomposition of these compounds.
- Dametto, P. R.,Caires, F. J.,Ambrozini, B.,Ionashiro, M.
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p. 831 - 836
(2011/11/04)
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- Thermal studies on solid 1,4-bis(3-carboxy-3-oxo-prop-1-enyl) benzene oflighter trivalent lanthanides
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Solid-state compounds of general formula Ln2L 3·nH2O, where L represents 1,4-bis(3-carboxy-3- oxoprop-1-enyl)benzene and Ln = La, Ce, Pr, Nd, Sm, were synthesized. Complexometric titrations with EDTA, thermogravimetry (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and infrared spectroscopy have been employed to characterize and to study the thermal behavior of these compounds in dynamic air atmosphere. The results led to information about the composition, dehydration, crystallinity, and thermal decomposition of the synthesized compounds.
- Nunes, Ronaldo S.,Bannach, Gilbert,Luiz, Jose M.,Caires, Flavio J.,Carvalho, Claudio T.,Ionashiro, Massao
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p. 525 - 530
(2012/01/31)
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- Comparison of covalency in the lanthanide chloride and nitrate complexes based on the adsorption data on zeolite y
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The changes of the distribution constants Kd of lanthanide chlorides in the system: zeolite Y (solid phase)-sodium chloride (aqueous phase) were investigated. The evident tetrad effect in the change of log Kd values within the lantha
- G?adysz-P?aska, Agnieszka,Majdan, Marek,Ferenc, Wies?awa,Sarzyński, Jan
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p. 469 - 474
(2012/03/22)
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- Synthesis, characterization and thermal behaviour of solid-state compounds of light trivalent lanthanide succinates
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Characterization, thermal stability and thermal decomposition of light trivalent lanthanide succinates, Ln2(C4H4O4)3 ·nH2O (Ln = La to Gd, except Pm) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), infrared spectroscopy, TG-FTIR system, elemental analysis and complexometry. The dehydration of the lanthanum and cerium compounds occurs in a single step, while for the praseodymium to gadolinium compounds the dehydration occurs in two consecutive steps. The thermal decomposition of the anhydrous compounds occurs in consecutive and/or overlapping steps, except for the cerium compound, with formation of the respective oxides, CeO2, Pr6O11 and Ln2O3 (Ln = La, Nd to Gd), as final residue. The results also provided information concerning the denticity of the ligand and thermal behaviour of these compounds.
- Lima,Caires,Carvalho,Siqueira,Ionashiro
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- Structural characterization of methanol substituted lanthanum halides
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The first study into the alcohol solvation of lanthanum halide [LaX3] derivatives as a means to lower the processing temperature for the production of the LaBr3 scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(μ-Br)(H2O)7](Br)2}2 (1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H2O)7(MeOH)2](Br)3 (2) compound was isolated where the La metal center retains its original 9-coordination through the binding of two additional MeOH solvents but necessitates the transfer of the innersphere Br to the outersphere. In an attempt to in situ dry the reaction mixture of 1 in MeOH over CaH2, crystals of [Ca(MeOH)6](Br)2 (3) were isolated. Compound 1 dissolved in MeOH at reflux temperatures led to the isolation of an unusual arrangement identified as the salt derivative {[LaBr2.75·5.25(MeOH)]+0.25 [LaBr3.25·4.75(MeOH)]-0.25} (4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr3 in MeOH forming the 8-coordinated [LaBr3(MeOH)5] (5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated (4 concentrated; 5 dilute) The other LaX3 derivatives were isolated as [(MeOH)4(Cl)2La(μ-Cl)]2 (6) and [La(MeOH)9](I)3·MeOH (7). Beryllium Dome XRD analysis indicated that the bulk material for 5 appear to have multiple solvated species, 6 is consistent with the single crystal, and 7 was too broad to elucidate structural aspects. Multinuclear NMR (139La) indicated that these compounds do not retain their structure in MeOD. TGA/DTA data revealed that the de-solvation temperatures of the MeOH derivatives 4-6 were slightly higher in comparison to their hydrated counterparts.
- Boyle, Timothy J.,Ottley, Leigh Anna M.,Alam, Todd M.,Rodriguez, Mark A.,Yang, Pin,Mcintyre, Sarah K.
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p. 1784 - 1795
(2010/07/03)
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- Synthesis, characterization and thermal behavior on solid tartrates of light trivalent lanthanides
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Solid state Ln-L compounds, where Ln stands for light trivalent lanthanides (L-Gd) and L is tartrate, have been synthesized. Thermogravimetry and differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry,
- Ambrozini,Dametto,Siqueira,Carvalho,Ionashiro
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p. 761 - 764
(2010/01/05)
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- Macrocyclic receptor exhibiting unprecedented selectivity for light lanthanides
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We report a new macrocyclic ligand, N,N'-bis[(6-carboxy-2-pyridil)methyl]- 4,13-diaza-18-crown- 6 (H2bp18c6), designed for complexation of lanthanide ions in aqueous solution. Potentiometric measurements evidence an unprecedented selectivity of bp18c6 for the large LnIIIions. Among the different LnIII ions, LaIII and CeIII show the highest log KML values, with a dramatic drop of the stability observed from CeIII to LuIII asthe ionic radius of the LnIII ions decreases (log Cel- log KLul ) 6.9). The X-ray crystal structures of the GdIII and YbIII complexes show that the metal ion is directly bound to the10 donor atoms of the bp18c6 ligand. The structure of the complexes in solution has been investigated by 1H and 13C NMR spectroscopy, as well a s by theoretical calculations performed at the DFT (B3LYP) level. Our results indicate that a conformational change occurs around the middle of the lanthanide series: for the larger LnIII ions the most stable conformation is Δ( δ λδ)( δ λδ), while for the smallest LnIII ions (Gd-Lu) our calculations predict the Δ(λδ λ)( λδ λ form being the most stable one. This structural change was confirmed by the analysis of the Ce III-, PrIII-, and YbIII-induced paramagnetic 1H shifts. The selectivity that bp18c6 shows for the large LnIII ions can be attributed to a better fit between the light LnIII ions and the relatively large crown fragment of the ligand. Indeed, our DFT calculations indicate that the interaction between the LnIII ion and several donor atoms of the crown moiety is weakened as the ionic radius of the metal ion decreases.
- Roca-Sabio, Adrian,Mato-Iglesias, Marta,Esteban-Gomez, David,Toth, Eva,Blas, Andres de,et al.
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p. 3331 - 3341
(2009/07/30)
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- Stability, water exchange, and anion binding studies on lanthanide(III) complexes with a macrocyclic ligand based on 1.7-diaza-12-crown-4: Extremely fast water exchange on the Gd3+ complex
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The picolinate-derivative ligand based on the 1,7-diaza-12-crown-4 platform (bp12c4 2-) forms stable Ln3+ complexes with stability constants increasing from the early to the middle lanthanides, then being relatively constant for the
- Palinkas, Zoltan,Roca-Sabio, Adrian,Mato-lglesias, Marta,Esteban-Gomez, David,Platas-Iglesias, Carlos,De Blas, Andres,Rodriguez-Blas, Teresa,Toth, Eva
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p. 8878 - 8889
(2009/12/25)
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- Dehydration and oxidation in the preparation of Ce-doped LaCl3 scintillation crystals
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Ce3+ activated LaCl3 is a promising scintillation crystal for radiation detection. The starting raw materials used to grow LaCl3 crystals are rather hygroscopic and XRD proves that LaCl3·7H2O and LaCl
- Ren, Guohao,Chen, Xiaofeng,Pei, Yu,Li, Huanying,Xu, Hongxiang
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p. 120 - 123
(2009/04/13)
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- Solubility behavior of rare earths with ammonium carbonate and ammonium carbonate plus ammonium hydroxide: Precipitation of their peroxicarbonates
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The purpose of this work is to report the significant behavior of the rare earths when treated with ammonium carbonate and with a binary mixture of ammonium carbonate plus ammonium hydroxide. The carbonates of some rare earths are completely soluble in ammonium carbonate or in ammonium carbonate plus ammonium hydroxide, while others are only partially soluble and finally some are completely insoluble. Addition of hydrogen peroxide to the soluble complexed rare earth carbonates results in the precipitation of a series of a new compounds described as rare earth peroxicarbonates. The rare earths have some different precipitation behavior in the carbonate-peroxide system. Some are completely and immediately precipitated, others are completely precipitated after an aging period, and finally other are not precipitated at all. These different behaviors open a new possibility for the separation chemistry of the rare earths. Sm, Gd, Dy, Y, Yb and Tm are fast and completely soluble in ammonium carbonate. Ho, Eu and Tb are completely soluble in ammonium carbonate but slowly dissolved. La, Ce, Pr and Nd are only partially soluble in ammonium carbonate. While Ce, Pr, Nd, Sm, Eu and Dy are completely and easily soluble in the ammonium carbonate plus ammonium hydroxide mixture, La is only partially soluble and Tb is completely insoluble in the same mixture. Concerning the peroxicarbonates, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy and Ho are quantitatively precipitated. The precipitation of the Er peroxicarbonate is quantitative, but after an aging period of 24 h. Y is not precipitated at all. The process is very easy, simple and economically attractive. Although proved in bench scale, its scale-up is easily feasible.
- de Vasconcellos, Mari E.,da Rocha,Pedreira,Queiroz, Carlos A. da S.,Abr?o, Alcídio
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p. 426 - 428
(2008/10/09)
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- Solid-state 2-methoxybenzoates of light trivalent lanthanides : SSSynthesis, characterization and thermal behaviour
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Solid-state LnL3 compounds, where L is 2-methoxybenzoate and Ln is light trivalent lanthanides, have been synthesized. Thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy and elemen
- Siqueira,Bannach,Rodrigues,Carvalho,Ionashiro
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p. 897 - 902
(2009/01/31)
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- Synthesis, potentiometric, kinetic, and NMR studies of 1,4,7,10- tetraazacyclododecane-1,7-bis(acetic acid)-4,10-bis(methylenephosphonic acid) (DO2A2P) and its complexes with Ca(II), Cu(II), Zn(II) and lanthanide(III) ions
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A cyclen-based ligand containing trans-acetate and trans- methylenephosphonate pendant groups, H6DO2A2P, was synthesized and its protonation constants (12.6, 11.43, 5.95, 6.15, 2.88, and 2.77) were determined by pH-potentiometry and 1H NMR spectroscopy. The first two protonations were shown to occur at the two macrocyclic ring N-CH 2-PO32- nitrogens while the third and fourth protonations occur at the two phosphonate groups. In parallel with protonation of the two -PO32- groups, the protons from the NH +-CH2-PO32- are transferred to the N-CH2-COO- nitrogens. The stability constants of the Ca2+, Cu2+, and Zn2+ (ML, MHL, MH2L, and M2L) complexes were determined by direct pH-potentiometry. Lanthanide(III) ions (Ln3+) form similar species, but the formation of complexes is slow; so, out-of-cell pH-potentiometry (La 3+, Eu3+, Gd3+, Y3+) and competitive spectrophotometry with Cu(II) ion (Lu3+) were used to determine the stability constants. By comparing the log KML values with those of the corresponding DOTA (H4DOTA = 1,4,7,10-tetraazacyclododecane-1,4, 7,10-tetraacetic acid) and DOTP (H8DOTP = 1,4,7,10- tetraazacyclododecane-1,4,7,10-tetramethylenephosphonic acid) complexes, the order DOTA 2+ complexes, for which the order is reversed. The relaxivity of Gd(DO2A2P) decreases between pH 2 and 7 but remains constant in the pH range of 7 1 = 3.6 mM-1 s-1). The linewiths of the 17O NMR signals of water in the absence and presence of Gd(DO2A2P) (at pH = 3.45 and 8.5) between 274 and 350 K are practically the same, characteristic of a q = 0 complex. Detailed kinetic studies of the Ce3+ and Gd3+ complexes with DO2A2P showed that complex formation is slow and involves a high stability diprotonated intermediate Ln(H2DO2A2P)*. Rearrangement of the diprotonated intermediate into the final complex is an OH- assisted process but, unlike formation of Ln(DOTA) complexes, rearrangement of Ln(H2DO2A2P)* also takes place spontaneously likely as a result of transfer of one of the protons from a ring nitrogen to a phosphonate group. The order of the OH- assisted formation rates of complexes is DOTA > DO2A2P > DOTP while the order of the proton assisted dissociation rates of the Gd3+ complexes is reversed, DOTP > DO2A2P > DOTA. 1H and 13C NMR spectra of Eu(DO2A2P) and Lu(DO2A2P) were assigned using two-dimensional correlation spectroscopy (2D COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear chemical shift correlation (HETCOR), and exchange spectroscopy (EXSY) NMR methods. Two sets of 1H NMR signals were observed for Eu(DO2A2P) characteristic of the presence of two coordination isomers in solution, a twisted square antiprism (TSAP) and a square antiprism (SAP), in the ratio of 93% and 7%, respectively. Line shape analysis of the 1H NMR spectra of Lu(DO2A2P) gave lower activation parameters compared to La(DOTP) for interconversion between coordination isomers. This indicates that the Ln(DO2A2P) complexes are less rigid probably due to the different size and spatial requirements of the carboxylate and phosphonate groups.
- Kalman, Ferenc K.,Baranyai, Zsolt,Toth, Imre,Banyai, Istvan,Kiraly, Robert,Bruecher, Ernoe,Aime, Silvio,Sun, Xiankai,Sherry, A. Dean,Kovacs, Zoltan
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p. 3851 - 3862
(2009/02/02)
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- Synthesis, Characterization and thermal behaviour of hemimellitic acid complexes with lanthanides(III)
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The complexes of lanthanides(III) with hemimellitic acid (1,2,3-benzenetricarboxylic acid, H3btc) of the formula Ln(btc)?nH2O, where Ln=lanthanide(III) ion and n=2-6 were prepared and characterized by elemental analysis, infrared spe
- Lyszczek
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p. 595 - 599
(2008/10/09)
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- Comparison of thermal properties of lanthanide trimellitates prepared by different methods
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By diffusion in gel medium new complexes of formulae: Nd(btc) ·6H2O, Gd(btc)·4.5H2O and Er(btc)?5H2O (where btc=(C6H3(COO)33-) were obtained. Isomorphous compounds were crystallized in the
- Lyszczek, Renata
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p. 833 - 838
(2009/02/07)
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- A systemic study of stepwise chlorination-chemical vapor transport characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by alkaline chlorides as complex former
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A systematic study has been carried out for the stepwise chlorination-chemical vapor transport (SC-CVT) characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by the vapor complexes KLnCl4 and NaLnCl4 (Ln = Sc, Y and La-Lu) used NaCl and KCl as complex former, respectively. The results showed that the SC-CVT characteristics are similarly for NaCl and KCl as complex former, the main deposition temperature of the rare earth chlorides LnCl3 is in the increasing order ScCl3 3 3, and then with a systematically decreasing trend from the early lanthanide chlorides to the end one. The results also showed that the total transported amount of the produced chlorides is YCl3 > ScCl3, and they are much higher than that of most lanthanoid chlorides. For lanthanoids, the total transported amount of chloride increases systematically from the early lanthanoid chlorides to the end one except for EuCl3 and GdCl3 mediated by KCl and NaCl as complex former, respectively, which showed the divergence effect of Gd in the total transport efficiency. But there are some differences in SC-CVT characteristics of pure rare earth oxide mediated by KCl and NaCl as complex former, that is the main deposition temperature region for the same rare earth element was lower for KCl than that for NaCl as complex former except for LaCl3, CeCl3, YbCl3 and LuCl3, while the total transport amount of rare earth chloride for KCl as complex former is higher than that for NaCl except for LaCl3 and EuCl3. More over, the discussion was carried out for Sc and Y on the one hand and the lanthanides contain 4f electron as another hand based on the 4f electron hybridization assumption. Further more, the transport characteristics of rare earth oxides with alkaline chlorides as complex former in this study were compared to that with AlCl3 as complex former.
- Sun, Yan-Hui,He, Peng,Chen, Hua-Ni
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p. 352 - 358
(2008/10/09)
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- Microcalorimetric studies on the interactions of lanthanide ions with bovine serum albumin
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The interactions of lanthanide ions (Ln3+) with bovine serum albumin (BSA) under mimetic physiological conditions (310.15 K, pH 6.7, 0.1MNaCl) were studied by microcalorimetry. For the first time, based on Two Sets of Independent Sites Model, m
- Li,Wang,Li,Wang
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p. 899 - 905
(2008/10/09)
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- Synthesis, characterization and thermal behaviour of solid-state compounds of yttrium and lanthanide benzoates
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Solid-state Ln(Bz)3?H2O compounds where Ln stands for trivalent yttrium or lanthanides and Bz is benzoate have been synthesized. Simultaneous thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffractometry, infra
- Locatelli,Rodrigues,Siqueira,Ionashiro,Bannach,Ionashiro
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p. 737 - 746
(2008/10/09)
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- Thermal and spectroscopic investigations of new lanthanide complexes with 1,2,4-benzenetricarboxylic acid
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The new 1,2,4-benzenetricarboxylates of lanthanide(III) of the formula Ln(btc)?nH2O, where btc is 1,2,4-benzenetricarboxylate; Ln is La-Lu, and n=2 for Ce; n=3 for La, Yb, Lu; and n=4 for Pr-Tm were prepared and characterized by elemental analy
- Lyszczek
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p. 533 - 539
(2008/10/09)
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- Equilibria and structure of the lanthanide(III)-2-hydroxy-1,3- diaminopropane-N,N,N′,N′-tetraacetate complexes: Formation of alkoxo-bridged dimers in solid state and solution
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The complex formed between 1,3-diamino-2-hydroxypropane-N,N,N′, N′-tetraacetic acid (H4L-OH) and Nd3+ at pH 7.5 was found to be a dinuclear dimer in the solid state by X-ray crystallography. In the complex K4[Nd2(L-O)2-(H2O) 2]-14H2O each ligand is coordinated to both Nd 3+ atoms with an iminodiacetate group (the Nd3+-Nd 3+ distance is 3.9283(8) A). The alcoholic OH groups are deprotonated, and the alkoxo oxygens are coordinated to both Nd3+ in a bridging position. The Nd3+ ions are nine-coordinated with one water molecule per Nd(III) ion in the inner sphere. The complex K 4[Nd2(L-O)2(H2O)2] ·14H2O has an inversion center, and the space group is P1. Two of the K+ counterions are six-coordinated, while the other two K+ ions are eight-coordinated; polar polymeric water-K+ layers are formed between the apolar ligand layers via the bridging water molecules. The dinuclear dimer complexes are also present in aqueous solution. The proton relaxivities of the Gd3+ complex decrease with the increase of pH, and at pH > 6, the low relaxivity values indicate the probable absence of H2O in the inner sphere and the predominance of the eight-coordinated dimer species [Gd2(L-O)2]. 4- The results of ESI-TOF MS studies of the complexes of La 3+, Nd3+, and Lu3+ proved the formation of dinuclear dimers in dilute (0.25 mM) solutions. pH-potentiometric titrations indicate the formation of complexes with 1:1 (Ln(L-OH)-, Ln(HL-OH), and Ln2(L-O)24-) and 2:1 (Ln 2(L-O)+) metal-to-ligand ratios. The stability constants of the Ln(L-OH)- species increase from La3+ (log K = 10.19) to Lu3+ (log K = 14.08). The alcoholic OH group of the Ln(L-OH)- species dissociates at unusually low pH values. The pH range of dissociation shifts to lower and lower pH's with the increasing atomic number of the lanthanides. This pH range is about 4-7 for the La3+ complex and 1-4 for the Lu3+ complex. The results of 1D and 2D 1H and 13C NMR studies of the La3+ complex, the number and multiplicity of signals, and the values of coupling constants are in agreement with the dinuclear dimer structure of the complex in solution.
- Tircso, Gyula,Benyei, Attila,Bruecher, Erno,Kis, Anita,Kiraly, Robert
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p. 4951 - 4962
(2008/10/09)
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- Synthesis, characterization, thermal stability, reactivity, and antimicrobial properties of some novel lanthanide(III) complexes of 2-(N-salicylideneamino)-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene
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Two series of new lanthanide(III) complexes of the type [Ln(HSAT) 2(H2O)3Cl3] and [Ln(HSAT) 2(NO3)3], where Ln = La, Pr, Nd, Sm, Eu, Gd, Dy, Tm, Yb, or Lu, and HSAT = 2-(N-salicy
- Mohanan,Devi
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p. 600 - 609
(2008/10/09)
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- Comparative study of the mutual separation characteristics for binary mixed oxides Er2O3-Ln2O3 (Ln = Sc, Y, La, Nd, Sm, Gd and Ho) mediated by vapor complexes KLnCl4
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Mutual separation characteristics for a series of rare earth elements Sc, Y, La, Nd, Sm, Gd, Ho and Er from their binary oxide mixtures Er 2O3-Sc2O3, Er2O 3-Y2O3, Er2O3-La 2O3, Er2O3-Nd2O 3, Er2O3-Sm2O3, Er 2O3-Gd2O3 and Er2O 3-Ho2O3 has been investigated using a stepwise chlorination-chemical vapor transport (SC-CVT) reaction mediated by vapor complexes KLnCl4. The total transported yield of the chlorides produced from the oxide mixtures was in the order of ErCl3 > ScCl3, ErCl3 > YCl3, ErCl3 > LaCl3, ErCl3 > NdCl3, ErCl3 > SmCl3, ErCl3 > GdCl3 and HoCl3 > ErCl3, and the total separation factors are 13.0 for Er:Sc, 1.49 for Er:Y, 1.48 for Er:La, 1.15 for Er:Nd, 2.33 for Er:Sm, 2.72 for Er:Gd and 1.10 for Ho:Er. The largest separation factors 1213.8 for Er:Sc, 6.37 for Er:Y, 189.3 for Er:La, 100.6 for Er:Nd, 105.7 for Er:Sm, 27.8 for Er:Gd and 1.14 for Er:Ho in the lower temperature region, while 102.7 for La:Er, only 14.3 for Nd:Er, 16.7 for Sm:Er, 4.0 for Gd:Er and 2.04 for Ho:Er in the higher temperature region were observed, respectively. The results showed the obvious divergence effect of Gd both in the largest separation factors, the total separation factors and total transport efficiency. Furthermore, the results were discussed on the difference of ionic radius of Sc and Y on the one side and the lanthanoid elements of La, Nd, Sm, Gd, Ho and Er on the other hand, and verified that the ionic radius is one of the decisive factors only for lanthanide elements, not for Sc and Y.
- Sun, Yan-Hui,Chen, Zhen-Fei,Hu, Sheng-Liang
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p. 175 - 180
(2008/10/09)
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- Extraction of lanthanide chlorides by binary extractants based on phosphinic acid derivatives
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The extraction of lanthanide chlorides by methyltrioctylammonium dialkylphosphinate, dialkyl-monothiophosphinate, or dialkyldithiophosphinate in toluene was studied. In all cases, extractable MA3 compounds were formed in an organic phase. The extractability of metals increased in the order La a considerable effect on the distribution of the lanthanide salts. The extraction capacity of the binary extradants toward lanthanum chloride decreased in the order methyltrioctylammonium dialkylphosphinate > methyltrioctylammonium dialkylmonothiophosphinate > methyltrioctylammonium dialkyldithiophosphinate. Copyright
- Egorova,Belova,Voshkin,Zhilov,Khol'kin
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p. 1781 - 1784
(2008/10/09)
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