Complexes of heavy lanthanides witho-aminobenzoic acid

Anthranilates of Tb-Lu prepared in the reaction of the rare earth hydroxides withortho-aminobenzoic acid (anthranilic acid) have the general formulaLn(C₆H₄NH₂COO)₃·2H₂O whereLn=Tb, Dy, Ho, Er, Tm, Yb, Lu. The water molecules in the hydrated compounds are in the outer coordination sphere. On heating in air at 493K dehydration occurs and the anhydrous anthranilatesLn(C₆H₄NH₂COO)₃ are formed. On the basis of the IR spectra it was found that the metal in dihydrated anthranilates was simultaneously coordinated through amino and carboxyl groups whereas in anhydrous anthranilates only through the bidentate carboxyl group. From X-ray analysis it was stated that the anthranilatesLn(C₆H₄NH₂COO)₃·2H₂O are isostructural, whereas the anhydrous compoundsLn(C₆H₄NH₂COO)₃ are isostructural in the two groups Tb-Er and Tm-Lu.

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Die Komplexe der schweren Selteneerdmetalle mit Orthoaminobenzoesäure

Zusammenfassung Zur Darstellung der Verbindungen des TypsLn(C₆H₄NH₂COO)₃·2H₂O (mitLn=Tb bis Lu) wurde die berechnete Menge vonLn(OH)₃ und C₆H₄NH₂COOH-Lösung gemischt und bei 363K schnell zur Kristallisation gebracht. Die Produkte werden schnell abfiltriert, mit Wasser gewaschen und bis zur Gewichtskonstanz getrocknet. Die VerbindungenLn(C₆H₄NH₂COO)₃·2H₂O sind isostrukturell mit der Dichte ungefähr 1.6g·cm^–1 und geringer Löslichkeit in Wasser bei Raumtemperatur. Beim Erhitzen folgt zunächst Entwässerung bei 493 K, später Zersetzung zu Tb₄O₇ undLn ₂O₃. Die wasserfreien VerbindungenLn(C₆H₄NH₂COO)₃ sind isostrukturell in 2 Strukturtypen: Tb-Er and Tm-Lu. Die Infrarotspektren von wasserfreien Verbindungen und Doppelhydraten wurden registriert. Es wurde festgestellt, daß die Koordinierung der Seltenerdmetalle mit Liganden in den Dihydraten sowohl durch die Amino- als auch durch Carboxylgruppen erfolgt. In den wasserfreien Komplexen tritt die Koordinierung nur durch Carboxylgruppen auf.

     

Schiff base derivatives of lanthanons-synthesis of La(III), Pr(III) and Nd(III) derivatives of β-ketoimines derived from 2,4-pentanedione

Reactions of the isopropoxides of some of the lighter lanthanons with bidentate -ketoimines, such asAAH-n-C₄H₉ andAAH-C₆H₅ (donor system: N,OH) and tridentate -ketoimines such asAA(CH₂CH₂)H₂ andAA(CH₂CHCH₃)H₂ (donor system: HO,N.OH) have led to products of the typesLn(O-i-C₃H₇)_3n (AA-R) _n ,Ln(Oi-C₃H₇) (AAR') andLn ₂(AAR')₃ [Ln=La(III), Pr(III) or Nd(III);n=1 or 2;R=-n-C₄H₉ or-C₆H₅ andR'=-CH₂CH₂-or-CH₂CHCH₃-]. Some undergo exchange reactions with an excess oftert-butanol, leading to the corresponding complexesLn(O-tert-C₄H₉)_3n (AA-n-C₄H₉) _n andLn(O-tert-C₄H₉) (AA-CH₂CH₂). All these have been characterised by elemental analysis, molecular weight determinations and their ir spectra. A thermogravimetric analysis of the diisopropoxy derivatives has also been carried out.

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Schiff-Basen Derivate von Lanthaniden-Synthese von La(III), Pr(III) und Nd(III) chelaten mit -Ketoiminen

Zusammenfassung Reaktionen von Lanthanid-Isopropoxiden mit zweizähnigen -Ketoiminen [AAH-n-C₄H₉ undAAH-C₆H₅; Donorsystem: N,OH] und dreizähnigen -Ketoiminen [AA(CH₂CH₂)H₂ undAA(CH₂CHCH₃)H₂; Donorsystem: OH, N,OH] führten zu Produkten vom, TypLn(O-i-C₃H₇)_3-n (AA-R) _n ,Ln(O-i-C₃H₇) (AAR') undLn ₂(AAR')₃ [Ln=La(III), Pr(III) oder Nd(III);n=1 oder 2;R=n-C₄H₉ oder C₆H₅ undR'=CH₂CH₂ oder CH₂CHCH₃]. Einige Komplexe unterliegen bei Behandlung mit einem Überschuß vontert-Butanol einer Austauschreaktion, die zu den entsprechenden Butoxid-Komplexen führt [Ln(O-tert-C₄H₉)_3-n , (AA-n-C₄H₉) _n undLn(O-tert-C₄H₉) (AACH₂CH₂)]. Alle Derivate wurden mittels Elementaranalyse, Molgewichtsbestimmung und IR-Spektroskopie charakterisiert. Eine thermogravimetrische Analyse der Diisopropoxi-Derivate wurde ebenfalls ausgeführt.

     

Preparation and study of rare earth 4-aminosalicylates

Summary p-Aminosalicylates of Y, La and lanthanides prepared in the reaction of the ammoniump-aminosalicylate and lanthanide chlorides in solutions have the general formulaLn(C₇H₆O₃N)₃·nH₂O, wheren=3 for La, Ce;n=2 for Pr, Nd, Sm, Eu;n=0 for Y, Gd—Lu. Their solubilities in water are of the order of 10^–3 mol dm^–3. Heating above 350–450 K leads to dehydration and decomposition at the same time. The IR and X-ray spectra for the obtained complexes were recorded. It was found that only complexes of La—Nd are crystalline compounds. The way of metal-ligand coordination is discussed.

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Darstellung und Charakterisierung der Komplexe von Seltenen Erdmetallen mitp-Aminosalicylsäure

Zusammenfassung Zur Darstellung der Verbindungen des TypsLn(C₇H₆O₃N)₃·nH₂O (mitn=3 für La, Ce;n=2 für Pr, Nd, Sm, Eu;n=0 für Y, Gd—Lu) wurde die berechnete Menge von Ammonium-p-aminosalicylat undLnCl₃-Lösungen beipH5.8 gemischt und zur Kristallisation gebracht. Ihre Wasserlöslichkeit bei 298 K ist in der Größenordnung 10^–3 mol dm^–3. Beim Erhitzen erfolgt bei 350–450 K Entwässerung und Zersetzung zugleich. Die Infrarot- und Röntgenspektren der erhaltenen Komplexe wurden gemessen und dabei festgestellt, daß nur die La—Nd-Komplexe kristalline Verbindungen sind. Die Art der Koordination der Seltenerdmetalle mit den Liganden wird diskutiert.

     

Über die Auflösung der Seltenerdoxide in methanolischen Ammoniumacetatlösungen und die Darstellung von Verbindungen des TypsLn(OAc)3. 3NH4OAc. 1H2O bzw.Ln)OAc)3. 1 NH4OAc. 1H2O

Zusammenfassung Die Oxide der Lanthanide und des Yttriums lösen sich beim Erhitzen in methanol. Ammoniumacetatlösungen. Aus den Lösungen konnten Verbindungen vom TypLn(OAc)₃·3 NH₄ OAc· ·1 H₂O (Ln=La, Ce, Pr, Nd, Sm Eu, Gd, Tb, Dy, Ho) bzw. Ln(OAc)₃ 1 NH₄OAc 1 H₂O (Ln=Er, Yb, Y) isoliert werden.Die höheren Oxide PrO_1,83 und TbO_1,75 lösen sich nur unvollständig unter Valenzdisproportionierung. Der Löserückstand besteht aus PrO₂ bzw. TbO₂.

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The oxides of the lanthanides and yttrium are dissolved in the heat by methanolic ammonium acetate solutions. From the obtained solutions compounds of the typeLn(OAc)₃·3 NH₄ OAc· ·1 H₂O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho) andLn(OAc)₃·1 NH₄OAc·1 H₂O (Ln=Er, Yb, Y), respectively, could be isolated.The higher oxides PrO_1,83 and TbO_1,75 react incompletely and disproportionation of valence is observed. The residues consist of PrO₂ and TbO₂, respectively. *** DIRECT SUPPORT *** A3615112 00028

     

Thermal decomposition of lighter lanthanide selenate hydrates and their solid solutions

The thermal dehydration-decomposition of Ln₂(SeO₄)₃·nH₂O (wheren=12 forLn=Pr, Nd andn=8 forLn=Sm) and Pr_xLn_2−x(SeO₄)₃·nH₂O (wheren=12 forx=1.0 andLn=Nd;n=8 forx=0.2 and 1.0 in case ofLn=Sm) have been reported.

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Zusammenfassung Die thermische Dehydratation-Zersetzung von Ln₂(SeO₄)₃·nH₂O (mitn=12 fürLn=Pr, Nd undn=8 fürLn=Sm) und Pr_xLn_2−x(SeO₄)₃·nH₂O (mitn=12 fürx=1.0 undLn=Nd;n=8 fürx=0.2 und 1.0 in Falle vonLn=Sm) wurde beschrieben.

     

Thermal decomposition of rare earthp-aminosalicylates in air atmosphere

The conditions of thermal decomposition of thep-aminosalicylates of Y, La and the lanthanides from Ce(III) to Lu have been studied. On heating, the hydrated complexes of La and the light lanthanides decompose to the oxides with the intermediate formation of Ln₂[H₂N·C₆H₃(O)COO]₃. Only the complex of La decomposes to La₂O₃ through La₂[H₂N·C₆H₃(O)COO]₃ and La₂O₂CO₃. The anhydrous complexes of the heavy lanthanides decompose directly to the oxides, whereas the anhydrous complex of Y decomposes to Y₂O₃ via Y₂[H₂N·C₆H₃(O)COO]₃ formation. During heating, the hydrated complexes lose crystallization water and decompose simultaneously, and the endothermic effect of dehydration is masked by the strong exothermic effect of burning of the organic ligand.

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Zusammenfassung Es wurden die Bedingungen für die thermische Zersetzung derp-Aminosalicylate von Y, La und der Lanthanoide von Ce(III) bis Lu untersucht. Beim Erhitzen zersetzen sich die hydratierten Komplexe von La und der leichteren Lanthanoide unter Bildung des Zwischenproduktes Ln₂[H₂NC₆H₃(O)COO]₃ in ihre Oxide. Nur der Komplex mit La zersetzt sich zu La₂O₃ über die Zwischenstufen La₂[H₂NC₆H₃(O)COO]₃ und La₂O₂CO₃. Die wasserfreien Komplexe der schweren Lanthanoide zersetzen sich direkt in die Oxide, wÄhrend sich der wasserfreie Komplex von Y über die Bildung von y₂[H₂NC₆H₃(O)COO]₃ in y₂O₃ zersetzt. Beim Erhitzen verlieren die hydratierten Komplexe ihr Kristallwasser und zersetzen sich gleichzeitig, der endotherme Effekt der Dehydratation wird durch den starken exothermen Effekt der Verbrennung der organischen Liganden überdeckt.

     

Comparison of thermal properties of lanthanide trimellitates prepared by different methods

By diffusion in gel medium new complexes of formulae: Nd(btc)⋅6H₂O, Gd(btc)⋅4.5H₂O and Er(btc)·5H2O (where btc=(C₆H₃(COO)₃ ³⁻) were obtained. Isomorphous compounds were crystallized in the form of globules. During heating in air atmosphere they lose stepwise water molecules and then anhydrous complexes decompose to oxides. Hydrothermally synthesized polycrystalline lanthanide trimellitates form two groups of isomorphous compounds. The light lanthanides form very stable compounds of the formula Ln(btc)⋅nH₂O (where Ln=Ce−Gd and n=0 for Ce; n=1 for Gd; n=1.5 for La, Pr, Nd; n=2 for Eu, Sm). They dehydrate above 250°C and then immediately decomposition process occurs. Heavy lanthanides form complexes of formula Ln(btc)⋅nH₂O (_Ln=Dy−Lu). For mostly complexes, dehydration occurs in one step forming stable in wide range temperature compounds. As the final products of thermal decomposition lanthanide oxides are formed.     

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.     

Spectral and thermal studies of Y(III) and heavy lanthanide 4-chlorophthalates

Summary Complexes of heavy lanthanide(III) (Gd-Lu) and Y(III) with 4-chlorophthalic acid were prepared and their IR spectra, solubility in water at 295 K and thermal decomposition were investigated. When heated the complexes with general formula Ln₂[ClC₆H₃(CO₂)₂]₃·nH₂O where n=6 for Tb, Dy(III), n=4 for Gd, Ho and Er(III), n=2 for Tm-Lu(III) and n=3 for Y(III) decompose to the oxides Ln₂O₃, Tb₄O₇ with intermediate formation of oxochlorides LnOCl.     

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.     

4,5‐Dichlorophthalate‐Extended Lanthanide Coordination Polymers with Layer and Ribbon Motifs: Synthesis,Structure, and Luminescence

Five new 4,5‐dichlorophthalate (dcpa)‐extended lanthanide coordination polymers (CPs) with formulas [Ln₂(H₂O)(dcpa)₃]_n (Ln = Tb for 1 , Sm for 2 , Pr for 3 , and Nd for 4 ) and [Yb(H₂O)₂(dcpa)(Hdcpa)]_n ( 5 ) were solvothermally synthesized. Structural determinations demonstrate that CPs 1 – 4 are crystallographically isostructural, exhibiting an infinite two‐dimensional layer with dimeric {Ln₂(COO)₃} subunits extended by aromatic skeleton of fully deprotonated dcpa^2– connectors. In contrast, complex 5 features a one‐dimensional broad ribbon with centrosymmetric {Yb₂(COO)₂} subunits propagated by pairs of ditopic dcpa^2– ligands. Interestingly, the anionic dcpa^2– connector can serve as a good antenna ligand to sensitize the characteristic emissions of the different Ln^III ions in both the ultraviolet (for 1 – 3 ) and near‐infrared (for 4 and 5 ) regions.     

Studies on the Thermal Decomposition of Rare Earth Caproates

The thermal decomposition of rare earth caproates with general formula Ln(C₅H₁₁COO)₃ nH₂O, (where Ln=Y, La-Pr, n=l; Ln=Nd-Er, n=2; Ln=Tm-Lu, n=3) were studied in an air atmosphere. On heating, the hydrated caproates are dehydrated in one step and then the anhydrous complexes decompose to the oxides (Ln₂O₃, Pr₆O₁₁) with formation of the intermediate Ln₂O₂CO₃ (La, Pr-Gd) or directly to the oxides Ln₂O₃, CeO₂, Tb₄O₇(Y, Ce, Tb-Lu). Caproates of rare earth elements are liquefied during dehydration.     

Thermal and Spectral Studies of Y(III) and Lanthanide(III) Complexes with Mesaconic Acid

Y(III) and lanthanide(III) mesaconates were prepared as crystalline solids with general formula Ln₂(C₅H₄O₄)₃⋅nH₂O, where n=7 for La−Pr, n=4 for Y,Nd−Ho, n=8 for Er−Lu. IR spectra of the prepared mesaconates suggest that carboxylate groups are bidentate bridging anf chelating. During heating the hydrated complexes are dehydrated in one (Y, Nd−Lu) or two steps (La−Pr) and then decompose directly to oxides (Y, Ce, Pr, Sm, Gd−Lu) or with intermediate formation Ln₂O₂CO₃ (La, Nd, Eu). This revised version was published online in August 2006 with corrections to the Cover Date.     

Preparation and examination of properties of lanthanide chloride salts with hexamethylenetetramine

Summary New complex salts of lanthanide chlorides with hexamethylenetramine of the general formulaLnCl₃·2HMTA·nH₂O [Ln=La, Pr, Nd, Sm, Dy, Er;HMTA-hexamethylenetetramine N₄(CH₂)₆;n=8, 10, 12] have been obtained. On the basis of IR IR spectra (4000-200cm^–1) and Raman spectra (3000-300 cm^–1), changes in the coordination sphere structure of the salts occurring in the course of thermal dehydration have been determined.

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Darstellung und Untersuchung der Eigenschaften von Komplexsalzen der Lanthanidchloride mit Hexamethylentetramin

Zusammenfassung Neue Komplexsalze der Lanthanidchloride mit Hexamethylentetramin mit der allgemeinen FormelLnCl₃·2HMTA·nH₂O [Ln=La, Pr, Nd, Sm, Dy, Er;HMTA — Hexamethylentetramin N₄(CH₂)₆;n=8, 10, 12] wurden dargestellt. Die Änderungen in der Struktur der Koordinationssphäre während der thermischen Dehydration der Salze wurden mittels Infrarot-(4 000–200 cm^–1) und Ramanspektroskopie (3 000–300 cm^–) bestimmt.

     

Thermal behaviour of mixed long-chain alkylammonium tetrachlorozincates

Mixed crystals of composition (n-C_mH_2m+1NH₃)_2xm(n-C_nH_2n+1 · NH₃)_2?2xm ZnCl₄ (m= 12; n=14, 16, 18) are formed upon annealing mechanical mixtures of layer compounds (n-C_nH_2n+1NH₃)₂ZnCl₄, through solid state diffusion of the n-alkylammonium cations. From a common high temperature monophasic modification, in which the polymethylenic chains are conformationally molten, different modifications are obtained on cooling [depending on the (n ? m) value] in which chain crystallinity is developed. The structure of such modifications is speculated on the grounds of DSC and preliminary X-ray diffractometric and IR data, and compared with that of similar previously characterized systems.     

Thermal decomposition of rare earth complexes withm-aminobenzoic acid

The conditions of thermal decomposition of the m-aminobenzoates of Y, La, Ce(III), Pr, Nd and Sm-Lu, Ln(C₆H₄NH₂COO)₃.nH₂O (n=4–6), have been studied.The hydrated compounds lose all molecules of crystallization water in one stage at 333–413 K. The anhydrous compounds are stable up to 570 K and are then decomposed exothermically to oxides.

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Zusammenfassung Es wurden die Bedingungen für die thermische Zersetzung derm-Aminobenzoate Ln(C₆H₄NH₂COO)₃.nH₂O (n=4–6) von Y, La, Ce(III), Pr, Nd und Sm-Lu untersucht. Alle Verbindungen geben ihr Kristallwasser in einem Schritt bei einer Temperatur zwischen 333 und 413 K ab. Die wasserfreien Verbindungen sind bis 570 K stabil und zersetzen sich dann exotherm unter Entstehung von Oxiden.

     

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.

     

Structural investigation of one‐ and three‐dimensional lanthanide(III) coordination polymers based on functionalized terpyridine carboxylate and aromatic dicarboxylate ligands

Three series of lanthanide coordination polymers, namely catena‐poly[[lanthanide(III)‐μ₂‐(benzene‐1,2‐dicarboxylato)‐μ₂‐[2‐(2,2′:6′,2′′‐terpyridin‐4′‐yl)benzoato]] monohydrate], {[Ln(C₈H₄O₄)(C₂₂H₁₄N₃O₂)]·H₂O}_n or {[Ln(1,2‐bdc)(L)]·H₂O}_n, with lanthanide (Ln) = dysprosium (Dy, 1 ), holmium (Ho, 2 ) and erbium (Er, 3 ), poly[bis(μ₂‐benzene‐1,3‐dicarboxylato)bis[μ₂‐2‐(2,2′:6′,2′′‐terpyridin‐4′‐yl)benzoato]dilanthanide(III)], [Ln₂(C₈H₄O₄)₂(C₂₂H₁₄N₃O₂)₂]_n or [Ln₂(1,3‐bdc)₂(L)₂]_n, with Ln = gadolinium (Gd, 4 ), Ho ( 5 ) and Er ( 6 ), and poly[(μ₂‐benzene‐1,4‐dicarboxylato)[μ₂‐2‐(2,2′:6′,2′′‐terpyridin‐4′‐yl)benzoato]lanthanide(III)], [Ln(C₈H₄O₄)(C₂₂H₁₄N₃O₂)]_n or [Ln(1,4‐bdc)(L)]_n, with Ln = Dy ( 7 ), Ho ( 8 ), Er ( 9 ) and ytterbium (Yb, 10 ), were synthesized under hydrothermal conditions and characterized by elemental analysis, IR and single‐crystal X‐ray diffraction. Compounds 1 – 3 possess one‐dimensional loop chains with Ln₂(COO)₂ units, which are extended into three‐dimensional (3D) supramolecular structures by π–π interactions. Isostructural compounds 5 and 6 show 6‐connected 3D networks, with pcu topology consisting of Ln₂(COO)₂ units. Compounds 7 – 10 display 8‐connected 3D frameworks with the topological type rob , consisting of Ln₂(COO)₂ units. The influence of the coordination orientations of the aromatic dicarboxylate groups on the crystal structures is discussed.     

Structural, thermal, and spectral investigations of the lanthanide(III) biphenyl-4,4′-dicarboxylates

The lanthanide biphenyl-4,4′-dicarboxylates (bpdc) series of the general formulae Ln₂(bpdc)₃·nH₂O, where Ln = lanthanides from La(III) to Lu(III); bpdc = C₁₂H₅(COO) ₂ ^2? ; n = 4, 5 or 6 have been obtained by the conventional precipitation method. All prepared complexes were characterized by elemental analysis, simultaneous thermal analyses thermogravimetric-differential scanning calorimetry (TG–DSC) and TG–FT-IR, FT-IR, and FT-Raman spectroscopy as well as X-ray diffraction patterns measurements. In the whole series of analyzed complexes the bpdc^2? ligand is completely deprotonated. In view of that, four carboxylate oxygen atoms are engaged in the coordination of Ln(III) ions. The synthesized compounds are polycrystalline and insoluble in water. They crystallize in the low symmetry crystal systems, like monoclinic and triclinic. Heating in the air atmosphere resulted in the multi-steps decomposition process, namely endothermic dehydration and strong exothermic decomposition processes. The dehydration process leads to the formation of stable anhydrous Ln₂bpdc₃ compounds which subsequently decompose to the corresponding lanthanide oxides.     

Thermal properties of lanthanide(III) complexes with 5-amino-1,3-benzenedicarboxylic acid

The complexes of yttrium(III) and lanthanides(III) with 5-amino-1,3-benzenedicarboxylic acid form two isostructural series of compounds and have the general formula Ln₂(C₈H₅O₄N)₃·nH₂O, where n = 13 for Y, La-Er and n=9 for Tm, Yb, Lu. They are insoluble in water and stable at room temperature. On heating in air or inert gas atmosphere they lose all water molecules in several steps. The anhydrous compounds are stable to about 400°C and next decompose to oxides.