Synthesis,structures and mass spectrometry of lanthanide nitrate complexes with tricyclohexylphosphine oxide

The complexes Ln(NO₃)₃(OPCy₃)₃(EtOH)_x (Cy = cyclohexyl, C₆H₁₁x = 0 for Ln = Eu, Er, x = 0.5 for Ln = La, Nd and x = 1 for Ln = Tm, Yb) have been prepared by reaction of lanthanide nitrates with Cy₃PO in ethanol. The single crystal X-ray structures for Ln = La, Nd, Eu, Er, Tm and Yb are reported. The structures for Ln = La–Eu have two molecules in the unit cell in which the nitrates are all bound as bidentate ligands. The unit cell for Ln = Er contains two distinct molecules; one with three bidentate nitrates and one with two bidentate and one monodentate nitrate. The Tm and Yb complexes have one molecule in the unit cell with two bidentate and one monodentate nitrate ligands. The monodentate nitrates are hydrogen bonded to ethanol in the Tm and Yb structures but not in the Er complex. The infrared spectra of the three classes of complex do not readily permit identification of the monodentate nitrate groups. Electrospray mass spectrometry indicates that redistribution/ionisation reactions occur in solution. Ions formed by solvolysis reactions are attributed to gas phase processes associated with the electrospray technique. Tandem mass spectrometry for the La, Ho and Yb complexes shows that in the gas phase loss of Cy₃PO is the sole fragmentation pathway for all but the Yb complex where the higher energy required for initial fragmentation leads to a more complex fragmentation pattern.     

Thermal behaviour of hydrated lanthanide complexes with heptanedioic acid

The multi-step dehydration and decomposition of trivalent lanthanum and lanthanide heptanediate polyhydrates were investigated by means of thermal analysis completed with infrared study. Further more, X-ray diffraction data for investigated heptanediate complexes of general stoichiometry Ln₂(C₇H₁₀O₄)₃.nH₂O (wheren=16 in the case of La, Ce, Pr, Nd and Sm pimelates,n=8 for Eu, Gd, Tb, Dy, Er and Tm pimelates,n=12 for Ho, Yb and Lu pimelates) were also reported.

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Zusammenfassung Mittels TG, DTG, DTA wurde in Verbindung mit IR-Methoden der mehrstufige Dehydratations- und der Zersetzungsvorgang der Polyhydrate der PimelinsÄuresalze von dreiwertigem Lanthan und dreiwertigen Lanthanoiden untersucht. Röntgendiffraktionsdaten der untersuchten Heptandiat-Komplexe mit der allgemeinen Formel Ln₂(C₇H₁₀O₄)₃ nH₂O (mitn=16 für Ln=La, Ce, Pr, Nd und Sm,n=8 für Ln=Eu, Gd, Tb, Dy, Er und Tm sowien=12 für Ln=Ho, Yb und Lu) werden ebenfalls gegeben.

     

Synthesis and single-crystal x-ray diffraction examination of a structurally homologous series of tetracoordinate heteroleptic anionic lanthanide complexes: Ln[N[Si(CH3)2CH2CH2Si(CH3)2]]3(mu-Cl)Li(L)3 (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb; (L)3 =(THF)3, (Et2O)3, (THF)2(Et2O)

Anhydrous lanthanide(III) chlorides (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) react with 3 equiv of lithium 2,2,5,5-tetramethyl-2,5-disila-1-azacyclopentanide, Li[N[Si(CH3)2CH2Ch2Si(CH3)2]], in THF or Et(2)O to afford the monomeric four-coordinate heteroleptic ate complexes Ln[N[Si(CH3)2CH2CH2Si(CH3)2]]3(mu-Cl)Li(THF/Et2O)3 (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Er (7), Tm (8), Yb (9)), whose solid-state structures were determined by the single-crystal X-ray diffraction technique. All complexes additionally were characterized by melting point determination, elemental analyses, and mass spectrometry.     

Syntheses, structure and rare earth metal photoluminescence of new and known isostructural A2Mo4Sb2O18 (A=Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) compounds

Nine new A₂Mo₄Sb₂O₁₈ (A=Ce, Pr, Eu, Tb, Ho, Er, Tm, Yb, Lu) compounds have been synthesized by solid-state reactions. They are isostructural with six reported analogues of yttrium and other lanthanides and the monoclinic unit cell parameters of all fifteen of them vary linearly with the size of A³⁺ ion. Single crystal X-ray structures of eight A₂Mo₄Sb₂O₁₈ (A=Ce, Pr, Eu, Gd, Tb, Ho, Er, Tm) compounds have been determined. Neat A₂Mo₄Sb₂O₁₈ (A=Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm) compounds exhibit characteristic rare earth metal photoluminescence.     

Trigonal Prismatic Coordination of Discrete Rare Earth Ions,Enforced by the Polyoxotungstate [P4W27O99(H2O)]16–

A family of solution-stable polyanions [Na⊂{Ln^III(H₂O)}{W^VIO(H₂O)}P^V₄W^VI₂₆O₉₈]¹²⁻ (Ln=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) represent the first examples of polyoxometalates comprising a single lanthanide(III) or yttrium(III) ion in a rare trigonal prismatic O₆ environment. Their synthesis exploits the reactivity of the organophosphonate-functionalized precursor [P₄W₂₄O₉₂(C₆H₅P^VO)₂]¹⁶⁻ with heterometal ions and yields hydrated potassium or mixed lithium/potassium salts of composition K_xLn_yH_12–x–y[Na⊂{Ln(H₂O)}{WO(H₂O)}P₄W₂₆O₉₈]⋅nH₂O⋅mLiCl (x=8.5–11; y=0–2; n=24–34; m=0–1.5). The Dy, Ho, Er and Yb derivatives are characterized by slow magnetization relaxation.     

Quest to enhance up-conversion efficiency: a comparison of anhydrous vs. hydrous synthesis of NaGdF4: Yb3+ and Tm3+ nanoparticles

A major challenge in the field of up-converting (UC) nanomaterials is to enhance their efficiencies. The –OH defects on the surface of the nanoparticles are thought to be the main cause of luminescence quenching, but there are no comparative studies in the literature showing the impact of anhydrous vs. hydrous synthesis on up-conversion efficiency. In this article, we present the synthesis of up-converting NaGdF₄: Yb⁺³, Tm⁺³ nanoparticles by two different methods: thermal decomposition of single source metal-organic anhydrous precursors [NaLn(TFA)₄(diglyme)] (Ln = Gd, Tm, Yb; TFA = trifluoroacetate) and room temperature co-precipitation using hydrated inorganic salts Ln(NO₃)₃·5H₂O (Ln = Gd, Tm, Yb), NaNO₃ and NH₄F in ethylene glycol. After a detailed study on the influence of solvents and the percentage of lanthanide dopant on the crystal phase of the up-converting nanoparticles (NPs) and their complete characterization, a comparative up-conversion study was carried out which revealed that the uniform nanospheres (av. size ～13 nm) obtained from the anhydrous SSP had significantly higher up-conversion efficiency than agglomerated nanorods (～197 nm in length and ～95 nm in width) produced from hydrated inorganic salts. An enhanced up-conversion quantum yield of 1.8% for the anhydrous sample validates the anhydrous precursor approach as a strategy to obtain small but highly emitting up-converting particles without requiring a silica or undoped matrix surface passivation layer.     

Hydrothermal phase equilibria in Ln2O3-H2O systems

Hydrothermal phase equilibria studies have been carried out in the Ln₂O₃-H₂O systems (Ln = La, Pr, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) and the stability fields of the phases Ln(OH)₃ LnOOH and Ln₂O₃-C have been established in the pressure-temperature range of 25000 psi and 900° C. The sequioxides Ln₂O₃-C are stable only in the last four systems of Er to Lu along with the Ln(OH)₃ and LnOOH. The systems from Nd to Ho have only Ln(OH)₃ and LnOOH as stable phases and those from La to Pr have only Ln(OH)₃ as the stable phase. The unit cell parameters of trihydroxides deviate from the values reported in the literature and this is attributed to the contamination of CO₂ in the starting material.     

Low temperature high-pressure synthesis of LnNiO3 (Ln = Eu,Gd) in molten salts

We report a new low temperature method for the synthesis of LnNiO₃ (Ln = Eu, Gd) at 400 °C under 180 bar oxygen pressure with the flux method. Utilization of the LiCl/KCl flux allowed for a decrease of the reaction temperature from 1000 °C and resulted in the synthesis of pure phase compounds. These materials have been characterized by powder X-ray diffraction and thermogravimetric analysis. LnNiO₃ (Ln = Eu and Gd) compounds crystallize in the orthorhombic GdFeO₃-type perovskite structure (space group: Pbnm). Both materials decompose to Ln₂O₃ and NiO at 775 °C under a nitrogen atmosphere and undergo reduction to Ln₂O₃ and Ni metal (at 385 °C and 340 °C for Eu and Gd, respectively) under a hydrogen atmosphere (10% H₂/N₂). Attempts to prepare the first T′-type infinite layer compound with Ni²⁺, EuNiO₂, by low temperature reduction of EuNiO₃ were unsuccessful.     

Heteroleptic polypyrazolylborate derivatives of the lanthanide ions. The synthesis of acetylacetonate derivatives and the molecular structures of [Ln{HB(C3N2H3)3}2{MeC(O)CHC(O)Me}] (Ln = Ce,Yb)

The air and moisture stable complexes [Ln{HB(C₃N₂H₃)₃}₂{MeC(O)CHC(O)Me}] (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Lu, Y), have been prepared and characterized. The molecular structures of the compounds with Ln = Ce and Yb reveal that a substantial distortion of the coordination geometry found for Ce³⁺ is necessary to allow the ligand set to accommodate the smaller Yb³⁺ ion.     

A series of three-dimensional coordination polymers with general formula [{Ln(H2O)n}{Re6Te8(CN)6}] · xH2O (Ln = Eu,Gd, Tb,Dy, Ho,Er, Tm,Yb; n = 3, 4, x = 0, 2.5)

A series of new compounds containing rare earth cations (Eu to Yb) and paramagnetic cluster anion [Re₆Te₈(CN)₆]³⁻ was prepared and investigated. The X-ray structural analyses have revealed that the compounds [{Ln(H₂O)₄}{Re₆Te₈(CN)₆}] · 2.5H₂O; Ln = Eu (1), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), [{Gd(H₂O)₃}{Re₆Te₈(CN)₆}] · 2.5H₂O (2) and [{Yb(H₂O)₄}{Re₆Te₈(CN)₆}] (8) are three-dimensional polymers based on Re–CN–Ln interactions. Measurements of magnetic susceptibility for 2 and 5 showed that effective magnetic moment (at 300 K) was 8.13 μ_B for compound 2 and 10.79 μ_B for compound 5 with weak antiferromagnetic ordering appeared at low temperatures.     

Molar enthalpies of formation of LnAl2 compounds

The enthalpy of solution of Eu in Al and the standard molar enthalpy of formation of LnAl₂ (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) were determined by dissolution calorimetry, using a calorimeter based on liquid aluminium. Experimental results are compared with model predictions.     

A study of the formation and application of new chiral water soluble lanthanoid benzoates using real-time infrared spectroscopy

A range of water soluble lanthanoid benzoate complexes of composition [Ln(Bz)₃(H₂O)_n] (Ln = La, Gd, Ho and Yb; Bz = 3,5-bis((R)-2,3-dihydroxypropoxy)benzoate and 3,4,5-tris((R)-2,3-dihydroxypropoxy)benzoate) have been prepared by reaction of lanthanoid bicarbonates with three equivalents of the corresponding optically active benzoic acid in water. Application of [Ln(Bz)₃(H₂O)_n] as asymmetric catalysts for epoxide ring opening reactions has been investigated using styrene oxide, showing complete conversion after 20 h, albeit with no significant enantiomeric excess observed. The formation of the lanthanoid complexes and subsequent catalytic conversion of styrene oxide to phenylethane-1,2-diol were monitored using real-time infrared (RTIR) spectroscopy, yielding information about reaction pathways and intermediates.     

Palladium(II)–rare-earth metal(III) paddlewheel carboxylate complexes: Easy total acetate to pivalate metathesis

Bis-paddlewheel heterobimetallic complexes in which palladium(II) is connected to the rare-earth metals(III) [Pd(μ-OOCMe)₄Ln(OH₂)(μ,η²-OOCMe)]₂ × 2HOOCMe (Ln = Nd, Sm, Eu, Yb and Tm) by four acetate bridges were synthesised by the reaction of Pd₃(μ-OOCMe)₆ with the Ln^III acetates. The tetraacetate-bridged complexes were unexpectedly found to be readily transformed by the stoichiometric amount of pivalic acid into the mono-paddlewheel tetrapivalate-bridged analogues in which the paddlewheel structure [Pd(μ-OOCR)₄Ln] maintains as established by X-ray crystallography. The role of the intra- and intermolecular H-bonding in these complexes is discussed.     

Structural features of thiocarbamide derivatives of some lanthanide iodides

Data on the synthesis, IR spectroscopy, and single crystal XRD are presented for thiocarbamide compounds of the composition [Ln(H₂O)₉]I₃·2CS(NH₂)₂, where Ln = Dy (I) and Yb (II). The structural features of [Ln(H₂O)₉]I₃·2CS(NH₂)₂ (Ln = Pr, Nd, Eu, Gd, Dy, Ho, Er, and Yb) are discussed. The compounds of thiocarbamide with Pr, Nd, Eu, Gd, and Dy iodides are found to form the first isostructural series characterized by a continuous network structure, while with Ho, Er, and Yb iodides the second isostructural series with a layered type structure is formed.     

Synthesis,crystal structure of Gd(H2O)(C2O4)2 · NH4 and of La(C2O4)2 · NH4. Characterization of the Ln(H2O)(C2O4)2 · NH4 with Ln=Eu…Yb

Single crystals of two lanthanide complexes, presenting similar formula Ln(H₂O)_x(C₂O₄)₂ · NH₄ with Ln=La, x=0 and Ln=Gd, x=1, have been prepared, in closed system at 200 °C. The gadolinium complex is bi-dimensional. A layer is built by the packing of the basic unit, [Gd(C₂O₄)]₄. The gadolinium atoms are related only by bischelating oxalate ligands, the ammonium ion and the water molecule (bound to the gadolinium atom) are localized into the interlayer space. The lanthanum complex is tri-dimensional. The basic building unit remains approximately the same and the packing of these units form a layer. However, within these units, the lanthanum atoms are related by either an oxalate ligand or an edge. Moreover, an oxalate ligand assumes the connection between the layers. The ammonium ion is localized into two sets of intersecting channels. Pure phase of the gadolinium complex has been prepared at 100 °C and extended to some lanthanide elements, Eu…Yb. As the size of the lanthanide ionic radius is decreasing, it is noticeable that the a unit–cell constant follows an expansion pattern while the others two follow an usual contraction one. The thermal behavior of this family shows that the anhydrous compounds are obtained and that some water molecule is sorbed during the cooling. Thus, the anhydrous compounds present a relatively open-framework with some small micropores.     

Synthesis of heterobimetallic lanthanide <Emphasis Type="Italic">tert</Emphasis>-butoxides and their catalytic properties in reactions of CO<Subscript>2</Subscript> with epoxides

Heterobimetallic tert-butoxides (t-BuO)₅Cu₂Ln (Ln = Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb), (t-BuO)₅MLa (M = Mn, Fe, Co, Ni), (t-BuO)₅ZnNd, and (t-BuO)₄ZnFe were prepared in high yields by the reaction of t-BuOLi with a stoichiometric mixture of a lanthanide halide LnX₃ (Ln = Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb; X = Cl, I) and a d-transition metal salt MX_n (M = Zn, Cu, Mn, Fe, Co, Ni; X = Cl, Br). (t-BuO)₅Cu₂Ln (Ln = Y, La, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) and (t-BuO)₅ZnNd at room temperature and atmospheric pressure induce copolymerization of CO₂ with cyclohexene oxide, affording the polycarbonate in a yield of 3–6 g g^–1 catalyst. The complex (t-BuO)₅FeLa, and also iron alcoholates (t-BuO)₂Fe and (t-BuO)2_Fe(bipy) under similar conditions catalyze the reaction of CO₂ with propylene oxide affording monomeric propylene carbonate in a yield of 35–45 g g^–1 catalyst.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1295–1299.Original Russian Text Copyright © 2004 by Nikitinskii, L. Bochkarev, Khorshev, M. Bochkarev.This revised version was published online in April 2005 with a corrected cover date.     

On the potentially excellent reducing ability of a series of low-valent rare earths induced by photoirradiation

Mixed systems of a series of rare earth metals such as La, Ce, Pr, Nd, Sm, Eu, and Yb and their low-valent rare earth diiodides exhibit excellent reducing ability toward the reductive deiodation from 1-iodododecane as a model compound compared with their single systems. More importantly, under photoirradiation conditions, the C-I bond reduction using ‘Ln/LnI₂’ takes place efficiently in refluxing THF, even in the cases of heavy rare earths such as Gd, Tb, Dy, Ho, Er, and Tm.     

Vibrational spectra of hydrated rare earth orthophosphates

Weinschenkite-type LnPO₄·2H₂O (Ln is Gd, Tb, Dy, Ho, Y, Er, Tm or Yb) and rhabdophane-type, LnPO₄·H₂O (Ln is La, Ce, Pr, Nd, Sm, Eu, Gd, Tb or Dy) have been investigated by IR absorption spectroscopy (4000–400 cm⁻¹) and Raman scanning spectroscopy (1400–100 cm⁻¹).The IR spectra of weinschenkite-type LnPO₄·2H₂O (Ln is Gd→Yb) are characterized by a band at 750±6 cm⁻¹ and the occurrence of a doublet in the region of the HOH bending vibrations, the low-frequency component exceeding the first high-frequency component in intensity. This rather peculiar pattern has already been observed in other compounds of similar chemical composition and is interpreted as arising from the presence of water molecules coordinated to the same metal cation. The Raman and IR spectra of these compounds have been interpreted in a manner based on the known structure of CaSO₄·2H₂O, which is isostructural with the weinschenkite-type compounds.The Raman and IR spectra of rhabdophane-type LnPO₄·H₂O is analyzed on the basis of the knowledge of the space group of rare earth orthophosphates rhabdophane-type. Its relation with the spectra of rare earth orthophosphates weinschenkite-type is discussed.     

Reactions of heavier lanthanides with hydrazine in the presence of sulphur dioxide

Hydrazine hydrate reacts with sulphur dioxide in aqueous solution in the presence of heavier lanthanide(III) ions to give variety of complexes. The nature of product formed is highly pH dependent. Several hydrazine complexes of Ln(III) ions of the compositions Ln(N₂H₃SOO)₃(H₂O), Ln₂(SO₃)₃·2N₂H₄ and N₂H₅Ln(SO₃)₂(H₂O)₂ where Ln = Eu, Gd, Tb or Dy and the precursors for the hydrazinium lanthanide sulphite hydrates, the anhydrous lanthanide hydrazinecarboxylates, Ln(N₂H₃COO)₃ where Ln = Eu, Gd, Tb or Dy have been prepared and characterized by analytical, spectral, thermal and X-ray powder diffraction techniques. The infrared spectral data are in favour of the coordination of hydrazine and water molecules. These complexes decompose in three stages to yield respective oxides as final residue. The final residues were confirmed by their X-ray powder diffraction patterns and TG mass losses. The SEM photographs of some of the oxides show a lot of cracks indicating that large quantity of gases evolved during decomposition.     

Synthesis and structure of para‐toluene sulfonamide lanthanide complexes and their application in the polymerization of ε‐caprolactone

A series of para‐toluene sulfonamide ligands [TsNHPr‐i( HL ₁ ), TsNHBu‐t( HL ₂ ), TsNHPh( HL ₃ ), TsNHPhMe‐p( HL ₄ ), TsNHPhOMe‐p( HL ₅ )] were synthesized by amidation using para‐toluene sulfonyl chloride reacting with different primary amines. A series of homoleptic lanthanide complexes (Ln L₃, 1–10) (Ln = La, L = L₁ ( 1 ), Ln = Gd, L = L₂ ( 2 ), Ln = La, L = L₂ ( 3 ), Ln = Gd, L = L₂( 4 ), Ln = La, L = L₃ ( 5 ), Ln = Gd, L = L₃ ( 6 ), Ln = La, L = L₄ ( 7 ), Ln = Gd, L = L₄( 8 ), Ln = La, L = L₅ ( 9 ), Ln = Gd, L = L₅ ( 10 )) were prepared by amine elimination reactions of the ligands with Ln[N(SiMe₃)₂]₃ (Ln = La, Gd). Complexes 1 , 3 , 5 , 7 and 9 were all characterized by NMR spectra, and the structures of complex 3 was determined by single‐crystal X‐ray diffraction. Complex 3 crystallizes a binuclear cluster, consisting of two La³⁺ and six (TsNBu‐t)⁻ anions. Three (TsNBu‐t)⁻ anions are chelating to each La³⁺ as bidentate model with O and N forming three‐membered chelate rings; one of three anions is bridging to another La³⁺ via oxygen. All complexes were characterized using elemental analysis and infrared spectra. The catalytic properties of complexes 1–10 for the ring‐opening polymerization of ε‐caprolactone were studied and the results showed that all complexes are efficient initiators for this ring‐opening polymerization reaction.