Thermal decomposition of lanthanide(III) and Y(III) 3,4,5-trihydroxybenzoates: Preparation, properties

Complexes of lanthanides(III) (La-Lu) and Y(III) with 3,4,5-trihydroxybenzoic acid (gallic acid) were obtained and their thermal decomposition, IR spectra and solubility in water have been investigated. When heated, the complexes with a general formula Ln(C₇H₅O₅)(C₇H₄O₅)·nH₂O (n=2 for La-Ho and Y: n=0 for Er-Lu) lose their crystallization water and decompose to the oxides Ln₂O₃, CeO₂, Pr₆O₁₁, and Tb₄O₇, except of lanthanum and neodymium complexes, which additionally form stable oxocarbonates such as Ln₂O₂CO₃. The complexes are sparingly soluble in water (0.3·10^–5–8.3·10^–4 mol dm^–3).This revised version was published online in November 2005 with corrections to the Cover Date.     

Mixed-Ligand Europium Complexes with Toluic Acid

Europium complexes with toluic acid having the composition Eu(Tol)₃· nD · xH₂O, where Tol^–is the meta-toluate anion, D is 1,10-phenanthroline (n= 2, x= 1), 2,2"-dipyridyl, piperidine, diphenylguanidine, triphenylphosphine oxide (n= 1, x= 2), and H₂O (n= 0, x= 2), were synthesized. The spectroscopic and luminescence properties of these complexes were studied. The title compounds are thermally stable up to 270°C. According to IR spectroscopy, two modes of coordination of the toluate anion, i.e., monodentate and bidentate coordination, can be found in europium toluates.     

Interaction features of cerium (III) and europium (III) acetate and pivalate with monoethanolamine

The composition of mixed-ligand complexes of cerium (III) and europium (III) acetates and pivalates with monoethanolamine (MEA) depends on the synthesis conditions and the nature of carboxylate ligand. We prepared solid complexes [Ln(Piv)₃(MEA) _x ], where Ln = Ce, Eu; HPiv-2,2-dimethylpropionic (pivalic) acid; x = 1, 1.5, and gel-like hydroxocomplexes [Ln(Carb) _{n − x − y} ,(NO₃) _x (OH) _y (MEA) _w (H₂O) _z ], where Ln = Ce, n = 4; Ln = Eu, n = 3; HCarb is acetic acid (HAcet) or HPiv. The values of the coefficients x, y, w, and z depend on the synthesis conditions and heat treatment. Prepared compounds were characterized by IR and ¹H NMR spectroscopies, elemental and thermal analyses, and MALDI-MS. The ESI-MS method was used to characterize the processes occurring in the solutions.     

Lanthanide(III) Nitrate Complexes of Two 17 Membered N3O2-Donor Macrocycles

The interaction of lanthanide(III) ions with two N₃O₃-macrocycles, L¹ and L², derived from 2,6-bis(2-formylphenoxymethyl)pyridine and 1,2-diaminoethane has been investigated. Schiff-base macrocyclic lanthanide(III) complexes LnL¹(NO₃)₃ · xH₂O (Ln = Nd, Sm, Eu or Lu) have been prepared by direct reaction of L¹ and the appropriate hydrated lanthanide nitrate. The direct reaction between the diamine macrocycle L² and the hydrated lanthanide(III) nitrates yields complexes LnL²(NO₃)₃· H₂O only for Ln = Dy or Lu. The reduction of the Schiff-base macrocycle decreases the complexation capacity of the ligand towards the Ln(III) ions. The complexes have been characterised by elemental analysis, molar conductivity data, FAB mass spectrometry, IR and, in the case of the lutetium complexes, ¹H NMR spectroscopy.     

Structural studies on 3-acetyl-1,5-diaryl and 3-cyano-1,5-diaryl formazan chelates with cerium(III), thorium(IV) and uranium(VI)

Summary Solid complexes of 3-acetyl-1,5-diaryl and 3-cyano-1,5-diaryl formazans were prepared and characterized by elemental analysis, IR, NMR, TGA and DTA analyses. Based on these studies, the suggested general formula for the complexes is [M(HL) _m (OH^–) _n or (NO ₃ ^– or Cl^–) _x ·(H₂O) _y or (C₂H₅OH orDMSO) _z , where HL=formazanM=Ce³⁺, Th⁴⁺, and UO ₂ ²⁺ ,m=1–2,n=0–3,x=0–3,y=0–4 andz=0–3. The metal ions are expected to have coordination numbers 6–8.

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Strukturuntersuchungen an 3-Acetyl-1,5-diaryl- und 3-Cyan-1,5-diaryl-formazan-Chelaten mit Cer(III), Thorium(IV) und Uran(VI)

Zusammenfassung Die hergestellten Chelate wurden mittels Elementaranalyse, IR, NMR, TGA und DTA charakterisiert. Darauf basierend wird die generelle Formel [M(HL) _m (OH^–) _n bzw. (NO ₃ ^– oder Cl^–) _x ·(H₂O) _y oder (C₂H₅OH bzw.DMSO) _z ] vorgeschlagen, wobei HL=Formazan,M=Ce³⁺, Th⁴⁺ oder UO ₂ ²⁺ ,m=1–2,n=0–3,x=0–3,y=0–4 undz=0–3. Die Metallionen haben Koordinationszahlen von 6–8.

     

Antimony(III) Chloride Complexes with Benzylpyridines: Synthesis and Luminescence. Crystal Structure of Bis(2-benzylpyridinium) Pentachloroantimonate(III)

The antimony(III) chloride complexes with 2- and 4-benzylpyridine were synthesized and studied using elemental analysis, X-ray diffraction analysis, IR spectroscopy, and luminescence spectroscopy. The crystal structure of bis(2-benzylpyridinium) pentachloroantimonate(III) was determined. The crystals are triclinic: a = 9.628(1) Å, b = 15.284(2) Å, c = 19.174(2) Å, = 99.962(2)°, = 101.233(2)°, = 99. 216(2)°; Z = 4, (calcd) = 1.591 g/cm³, space group P , R = 0.0358. The structure consists of polymeric chains of [Sb₂Cl₁₀]^4n– _n anions and [C₁₂H₁₁NH]⁺ cations combined into a framework by the N–H···Cl hydrogen bonds. The electronic and geometrical factors responsible for a relatively low intensity of the luminescence emitted by the complexes of antimony(III) chloride with 2- and 4-benzylpyridine at 77 K are discussed.     

2D l‐Di‐toluoyl‐tartaric acid Lanthanide Coordination Polymers: Toward Single‐component White‐Light and NIR Luminescent Materials

A series of five l ‐di‐p‐toluoyl‐tartaric acid (l ‐DTTA) lanthanide coordination polymers, namely {[Ln₄K⁴ L₆(H₂O)_x]?yH₂O}_n, [Ln=Dy ( 1 ), x=24, y=12; Ln=Ho ( 2 ), x=23, y=12; Ln=Er ( 3 ), x=24, y=12; Ln=Yb ( 4 ), x=24, y=11; Ln=Lu ( 5 ), x=24, y=12] have been isolated by simple reactions of H₂L (H₂L= L ‐DTTA) with LnCl₃?6 H₂O at ambient temperature. X‐ray crystallographic analysis reveals that complexes 1 – 5 feature two‐dimensional (2D) network structures in which the Ln³⁺ ions are bridged by carboxylate groups of ligands in two unique coordinated modes. Luminescent spectra demonstrate that complex 1 realizes single‐component white‐light emission, while complexes 2 – 4 exhibit a characteristic near‐infrared (NIR) luminescence in the solid state at room temperature.     

Lanthanide-Containing Monomers Produced from Unsaturated Acids: Synthesis,Polymerization, and Spectral and Luminescent Properties. Crystal Structure of Europium(III) Methacrylate

Synthesis of lanthanide-containing (Ln = Eu, Tb, Nd, Gd) monomers based on unsaturated acids is described, namely, of LnL¹ ₃ · nH₂O (L¹ are anions of acrylic and methacrylic acids) and Ln₂L² ₃ · nH₂O (L² are anions of maleic and fumaric acids); n = 0–3, 6. The compounds were characterized by elemental analysis, thermogravimetry, and IR and luminescence spectroscopy. Europium methacrylate Eu(Macr)₃ was studied using X-ray diffraction analysis: rhombic system, a = 14.831(3) Å, b = 12.964(2) Å, c = 7.761(1) Å, space group Cmc2₁, V = 1483.5(4) ų, (calcd) = 1.823 g/cm³. Infinite chains of Eu(Macr)₃ molecules are directed along crystallographic axis c and are bound by van der Waals interactions. Radical polymerization of Eu(III) and Tb(III) acrylates and Eu(III) methacrylate yields lanthanide-containing polymers with a high content of Ln (40–50 mass %). Their spectral and luminescent properties are studied.     

Preparation, Spectral and Thermal Studies of Y(III) and Lanthanide(III) 1-Hydroxy-2-Naphthoates

Complexes of lanthanide(III) (La–Lu) and Y(III) with 1-hydroxy-2-naphthoic acid were obtained as crystalline compounds with a general formula Ln[C₁₀H₆(OH)COO]₃⋅nH₂O:n=6 for La–Tm and Y, n=2 for Yb and n=0 for Lu. IR spectra of the prepared complexes were recorded, and their thermal decomposition in air were investigated. Spectroscopic data suggest that in the coordination of metal-organic ligand only oxygen atoms from the carboxylate group take part. When heated, the complexes decompose to the oxides Ln₂O₃, CeO₂, Pr₆O₁₁ and Tb₄O₇ with intermediate formation of Ln(C₁₁H₇O₃)(C₁₁H₆O₃). This revised version was published online in August 2006 with corrections to the Cover Date.     

Conformational study of lanthanide(III) complexes of N-(2-salicylaldiminatobenzyl)-1-aza-18-crown-6 by using X-ray and ab initio methods

A structural study of lanthanide complexes with the deprotonated form of the monobracchial lariat ether N-2-salicylaldiminatobenzyl-aza-18-crown-6 (L⁴) (Ln = La(III)–Tb(III)) is presented. Attempts to isolate complexes of the heaviest members of the lanthanide series were unsuccessful. The X-ray crystal structures of [Pr(L⁴)(H₂O)](ClO₄)₂ · H₂O · C₃H₈O and [Sm(L⁴)(H₂O)](ClO₄)₂ · C₃H₈O show the metal ion being bound to the eight donor atoms of the ligand backbone. Coordination number nine is completed by the oxygen atom of an inner-sphere water molecule. Two different conformations of the crown moiety (labelled as A and B) are observed in the solid state structure of the Pr(III) complex, while for the Sm(III) complex only conformation A is observed. The complexes were also characterized by means of theoretical calculations performed in vacuo at the HF level, by using the 3-21G^∗ basis set for the ligand atoms and a 46 + 4fⁿ effective core potential for lanthanides. The optimized geometries of the Pr(III) and Sm(III) complexes show an excellent agreement with the experimental structures obtained from X-ray diffraction studies. The calculated relative energies of the A and B conformations for the different [Ln(L⁴)(H₂O)]²⁺ complexes (Ln = La, Pr, Sm, Ho or Lu) indicate a progressive stabilization of the A conformation with respect to the B one upon decreasing the ionic radius of the Ln(III) ion. For the [Ln(L⁴)(H₂O)]²⁺ systems, most of the calculated bond distances between the metal ion and the coordinated donor atoms decrease along the lanthanide series, as usually observed for Ln(III) complexes. However, our ab initio calculations provide geometries in which the Ln–O(5) bond distance [O(5) is an oxygen atom of the crown moiety] increases across the lanthanide series from Sm(III) to Lu(III).     

New complexes of lanthanide Ln(III), (Ln = La, Sm, Gd, Er) with Schiff bases derived from 2-furaldehyde and phenylenediamines

Some new Schiff bases derivates from 2-furaldehyde and phenylenediamines (L^1-3) and their complexes with lanthanum (La), samarium (Sm), gadolinium (Gd) and erbium (Er) have been synthesized. These complexes with general formula [Ln(L^1-3)₂(NO₃)₂]NO₃·nH₂O (Ln = La, Sm, Gd, Er) were characterized by elemental analysis, UV-Vis, FT-IR and fluorescence spectroscopy, molar conductivity and thermal analysis. The metallic ions were found to be eight coordinated. The emission spectra of these complexes indicate the typical luminescence characteristics of the Sm(III), La(III), Er(III) and Gd(III) ions.     

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.     

Study of isomorphism in fluorine-containing antimony(III) complexes

The mutual influence of the atoms on the composition of solid fluorine-containing antimony(iii) complexes formed in aqueous solutions in the (MF) _x −(M′F) _n−x −SbF₃ (M, M′=Na, K, Rb, Cs, and NH₄;n=1, 2;x=0 to 2), (KNO₂) _n −(KY) _n −SbF₃ (Y=F, Cl, SO₄;n=0.5, 1), and K₂SbF₅−K₂SbCl₅ systems was investigated by elemental, X-ray, and thermogravimetric analyses and by IR and^121,123Sb NQR spectroscopy. The isomorphism conditions for fluorine-containing antimony(iii) compounds resulting in the formation of complexes NaM′SbF₅·1.5H₂O (M′=K and Rb), K₂SbF₅·1.5H₂O, NaCs₃Sb₄F₁₆·H₂O, KsbF₃Cl, K₂SbF₂Cl₃ with constant compositions, continuous M _x M′_2−x SbF₅ (0<x<2) and limited M _x M′_1−x SbF₄ (0.25<x<0.75; M, M′=K, Rb, Cs, and NH₄) solid solutions or LiF+MSbF₄ (M=Na, K, Rb, and Cs), M₂SbF₅+Cs₂SbF₅ (M=Na and K) and MSbF₄+NaSbF₄ (M=Rb and NH₄) mechanical mixtures were determined. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 103–108, January, 1999.     

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.     

Syntheses and structures of layered compounds based on lanthanides(iii) and cubane molybdenum and tungsten telluride cyano complexes

Eight isostructural polymeric coordination compounds of the general formula [Ln(DMF)(H₂O)₄][Ln(DMF)₂(H₂O)₄][M₄Te₄(CN)₁₂]·DMF·nH₂O (Ln = Er, Ho, Gd, or Sm; M = W or Mo) were prepared for the first time by evaporation in air of aqueous solutions containing the cuboidal telluride anionic complex of tungsten [W₄Te₄(CN)₁₂]^6– or molybdenum [Mo₄Te₄(CN)₁₂]^7–, lanthanide chlorides, and dimethylformamide. The resulting polymeric coordination complexes with layered structures were characterized by X-ray diffraction analysis and IR spectra. The magnetic susceptibilities of the gadolinium complexes were measured.     

Synthesis,structure, and photophysical property of series of Ln(III) coordination polymers with different carboxylato ligands (Ln = Sm,Eu)

Four Ln(III) coordination polymers, {[Ln₂(1,3-bdc)₃(H₂O)₄]·DMF·H₂O} _n (Ln = Sm 1, Eu 2) and [Ln₂(mal)₃(H₂O)₆] _n (Ln = Sm 3, Eu 4) (1,3-H₂bdc = isophthalate acid, H₂mal = malonate acid), were hydrothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectra, UV–Vis–NIR absorption spectra, and fluorescence spectra. The structural analyses reveal that polymer 1 is a 3D coordination polymer. Its asymmetry unit contains two crystallographically independent Sm(III) ions, both are eight-coordinated. The 1,3-bdc^2? anions show three different coordination modes. The structure of polymer 2 is isomorphous with that of 1. Polymer 3 is also a 3D coordination polymer, its asymmetry unit contains one Sm(III) ion, which is nine-coordinate. The mal^2? anions have two different coordination modes. The structure of polymer 4 is isomorphous with that of 3. The luminescent study shows that polymers 1, 2, and 4 exhibit characteristic emission bands in the visible region, corresponding to the transitions of the Ln(III) ions. By comparison and analysis of luminescence, it is found that the incidence of the same ligand on the corresponding spectra of different Ln(III) ions is different, and the influence of different ligands on luminescence of the same Ln(III) ion is also very different.

     

Rare-earth metal allyl and hydrido complexes supported by an (NNNN)-type macrocyclic ligand: synthesis, structure, and reactivity toward biomass-derived furanics

The preparation and characterization of a series of neutral rare‐earth metal complexes [Ln(Me₃TACD)(η³‐C₃H₅)₂] (Ln=Y, La, Ce, Pr, Nd, Sm) supported by the 1,4,7‐trimethyl‐1,4,7,10‐tetraazacyclododecane anion (Me₃TACD^?) are reported. Upon treatment of the neutral allyl complexes [Ln(Me₃TACD)(η³‐C₃H₅)₂] with Brønsted acids, monocationic allyl complexes [Ln(Me₃TACD)(η³‐C₃H₅)(thf)₂][B(C₆X₅)₄] (Ln=La, Ce, Nd, X=H, F) were isolated and characterized. Hydrogenolysis gave the hydride complexes [Ln(Me₃TACD)H₂]_n (Ln=Y, n=3; La, n=4; Sm). X‐ray crystallography showed the lanthanum hydride to be tetranuclear. Reactivity studies of [Ln(Me₃TACD)R₂]_n (R=η³‐C₃H₅, n=0; R=H, n=3,4) towards furan derivatives includes hydrosilylation and deoxygenation under ring‐opening conditions.     

Cu(II) and Pd(II) complexes of N-(2-hydroxybenzyl)aminopyridines

N-(2-Hydroxybenzyl)aminopyridines (Lⁱ) react with Cu(II) and Pd(II) ions to form complexes in the compositions Cu(Lⁱ)₂(CH₃COO)₂ · nH₂O (n = 0, 2, 4), Pd(Lⁱ)₂Cl₂ · nC₂H₅OH (n = 0, 2) and Pd(L²)₂Cl₂ · 2H₂O. In the complexes, the ligands are neutral and monodentate which coordinate through pyridinic nitrogen. Crystal data of the complexes obtained from 2-amino pyridine derivative have pointed such a coordinating route and comparison of the spectral data suggests the validity of similar complexation modes of other analog ligands. Cu(II) complex of N-(2-hydroxybenzyl)-2-aminopyridine (L¹), [Cu(L¹)₂(CH₃COO)₂] has slightly distorted square planar cis-mononuclear structure which is built by two oxygen atoms of two monodentate carboxylic groups disposed in cis-position and two nitrogen atoms of two pyridine rings. The remaining two oxygen atoms of two carboxylic groups form two Cu and H bridges containing cycles which joint at same four coordinated copper(II) ion. IR and electronic spectral data and the magnetic moments as well as the thermogravimetric analyses also specify on mononuclear octahedric structure of complexes [Cu(L²)₂(CH₃COO)₂ · 2H₂O] and [Cu(L³)₂(CH₃COO)₂ · 4H₂O] where L² and L³ are N-(2-hydroxybenzyl)-2- or 3-aminopyridines, respectively.     

Substituted dipyridylpyridazine rhodium(III) complexes

3,6-Bis(2-pyridyl)pyridazine derivatives (n-dppn) react with hydrated rhodium(III) chloride and bromide (prepared in situ) to give cis-[Rh(n-dppn)₂Cl₂]PF₆·xH₂O (n = 5, 6, 7, 8) and cis-[Rh(n-dppn)₂Br₂]Br·xH₂O (n = 5, 7) complexes, which have been characterized by elemental analyses, conductivity measurements, i.r., electronic and ¹H- and ¹³C-n.m.r. spectra.     

Thermal,spectral and magnetic behaviour of 4-chloro-2-methoxybenzoates of light lanthanides(III)

4-Chloro-2-methoxybenzoates of light lanthanides(III) were obtained as mono-, di-or trihydrates with metal to ligand ratio of 1:3 and general formula Ln(C₈H₆ClO₃)₃·nH₂O, where n=1 for Ln=Ce, Pr, n=2 for Ln=Nd, Sm, Eu, Gd and n=3 for Ln=La. The complexes were characterized by elemental analysis, IR spectra, thermogravimetric studies, X-ray diffraction and magnetic measurements. The carboxylate group appears to be a symmetrical bidentate, chelating ligand. All complexes seem polycrystalline compounds. Their thermal stabilities were determined in air. When heated they dehydrate to form anhydrous salts which next are decomposed to the oxides of the respective metals. The solubilities of light lanthanide(III) 4-chloro-2-methoxybenzoates in water at 293 K are of the order of 10⁻⁵ mol dm⁻³. The magnetic moments were determined over the range of 77–300 K. They obey the Curie-Weiss law. The values of μ_eff calculated for all compounds are close to those obtained for Ln³⁺ by Hund and Van Vleck. 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.