Spectral and Thermal Studies of Rare Earth Element 3-methylglutarates

Conditions for the formation of rare earth element (Y, La–Lu) 3-methylglutarates were studied and their quantitative composition and solubilities in water at 293 K were determined (10^–2 mol dm^–3). The IR spectra of the prepared complexes with general formula Ln₂(C₆H₈O₄)₃ nH₂O (n=3–8) were recorded and their thermal decomposition in the air were investigated. During heating the hydrated 3-methylglutarates are dehydrated in one step and next anhydrous complexes decompose to oxides Ln₂O₃ with intermediate formation Ln₂O₂CO₃ (Y, La, Nd–Gd) or directly to the oxides, Ln₂O₃, CeO₂, Pr₆O₁₁ and Tb₄O₇ (Ce, Pr, Tb–Lu). This revised version was published online in August 2006 with corrections to the Cover Date.     

Studies on thermal decomposition of 3-chlorobenzoates of rare earth elements in air atmosphere

The conditions of thermal decomposition of the 3-chlorobenzoates of Y, La and the lanthanides from Ce(III) to Lu have been studied. The complexes of La, Pr(III), Sm, Eu, Gd, Tb(III) and Dy were prepared as heptahydrates, those of Ce(III) and Y as pentahydrates, that of Nd as the tetrahydrate, that of Ho as the dihydrate and those of Er, Tm, Yb and Lu as anhydrous salts. On heating, these complexes decompose in three or two stages. They first lose some water molecules and then decompose to oxides through the intermediate formation of LnOCl. Cerium(III) 3-chlorobenzoate loses its crystallization water in two stages and yields the anhydrous salt, which is then transformed directly into CeO₂. All these complexes melt before decomposition in the temperature range 441–513 K.     

Thermal decompositions of light lanthanide aconitates

The conditions of thermal decomposition of Y, La, Ce(III), Pr, Nd, Sm, and Gd aconitates have been studied. On heating, the aconitate of Ce(III) loses crystallization water to yield anhydrous salt, which then is transformed in to oxide CeO₂. The aconitates of Y, Pr, Nd, Sm, Eu and Gd decompose in three stages. First, aconitates undergo dehydration to form the anhydrous salts, which next decompose to Ln₂O₂CO₃. In the last one the thermal decomposition of Ln₂O₂CO₃ to Ln₂O₃ is accompanied by endothermic effect. Dehydration of aconitate of La undergoes in two stages. The anhydrous complex decomposes to La₂O₂CO₃; this subsequently decomposes to La₂O₃.     

Thermal decomposition of rare earth element enanthates

The conditions of formation of Y, La and lanthanide (from Ce(III) to Lu) enanthates were worked out, their composition and their solubilities in water at 291 K were determined, and the conditions of their thermal decomposition were studied. They were prepared as crystalline solids with general formula Ln(C₇H₁₃O₂)₃·nH₂O, wheren=2–10. On heating, they decompose in two or three steps. They first lose some water molecules and then decompose to the oxides directly (salts of Y and heavy lanthanides) or via the intermediate formation of Ln₂O₂CO₃ (salts of La, Pr, Nd, Sm and Eu). Only yttrium enanthate dihydrate loses 2 water molecules on heating to form an anhydrous complex, which decomposes directly to Y₂O₃. The temperatures of dehydration are similar for all complexes (323–343 K), while the temperatures of oxide formation vary irregularly from 823 K for CeO₂ to 1078 K for La₂O₃.     

Some Properties and Thermal Decomposition of Yttrium and Lanthanide Benzohydroxamates

The conditions of formation and some properties of yttrium and lanthanide benzohydroxamates were studied. Simultaneous TG-DTG-DTA studies under non-isothermal conditions were carried out in air atmosphere in the temperature range 20-1000°C. The IR spectra and X-ray patterns of some thermal decomposition products were recorded. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spectral and Thermal Studies of Rare Earth Complexes With 2,4,6-trimethylbenzoic Acid

The rare earth element 2,4,6-trimethylbenzoates were prepared as solids with the general formula Ln(C₁₀ H₁₁ O₂ )₃ ×n H₂ O, where n =2 for Ln =Y, La–Nd, and n =1 for Ln =Sm–Lu. The IR spectra of the complexes prepared were recorded and their solubilities in water and thermal decomposition in the air were investigated. During heating the hydrated complexes lose all the crystallization water molecules in one (Y, Ce–Lu) or two steps (La) and then the anhydrous complexes decompose either directly to oxides (Y, Ce, Pr, Sm–Lu) or with intermediate formation oxocarbonates Ln₂ O₂ CO₃ (La, Nd). The carboxylate groups in the complexes prepared act probably as mono- and bidentate. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal decompositions of Y,La and light lanthanide thiodiglycolates

The conditions of thermal decomposition of the thiodiglycolates of Y, La and light lanthanides from Ce to Gd have been studied. On heating, these complexes decompose in various ways. Hydrated thiodiglycolates of La,Ce(III), Pr(III) and Gd lose crystallization water in one step, while those of Y, Nd, Sm and Eu(III) do so in two steps. The anhydrous complexes subsequently decompose in several steps to the oxysulfates Ln₂O_3–x((SO₄)_x.

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Zusammenfassung Bedingungen der thermischen Zersetzung der Thiodiglycolate von Y, La und den leichten Lanthaniden von Ce bis Gd wurden untersucht. Beim Erhitzen zersetzen sich diese Komplexe auf verschiedene Weise. Hydratisierte Thiodiglycolate von La, Ce(III), Pr(III) und Gd verlieren das Kristallwasser in einem Schritt, die von Y, Nd, Sm, und Eu(III) dagegen in zwei Schritten. Die wasserfreien Komplexe zersetzen sich in mehreren Schritten zu den Oxysulfaten Ln₂O_3–x(SO₄)_x.

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. . . , , , , , . Ln₂O_3–x(SO₄)_x.

     

Preparation and properties of yttrium complexes with alkanodicarboxylic acids

Malonate, succinate and glutarate of yttrium were obtained by dissolving Y(OH)₃ in a solution of the corresponding acid and crystallization, whereas adipate, pimelate, suberate, azelate and sebacate in the reaction of YCl₃ with the ammonium salt of the acid. Yttrium alkanodicarboxylates were prepared as crystalline solids with general formula Y₂O₃.nH₂O, wheren=3, 4, 6, 7. On the basis of IR spectra the way of coordination COO^– - Y³⁺ was established. Yttrium malonate, succinate, glutarate, azelate and sebacate heated lose crystallization water and next anhydrous complexes are transformed to Y₂O₃, whereas yttrium adipate, pimelate and suberate on heating lose some water molecules and, the mono- or dihydrates formed are decomposed to Y₂O₃. The properties of the studied complexes change discretely according to odd or even number of carbon atoms in the chain.

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Zusammenfassung Durch Auflösen von Y(OH)₃ in einer Lösung der entsprechenden Säure und anschliessendem Kristallisieren wurden Yttriummalonat,-succinat und -glutarat dargestellt, das Yttriumadipat, -pimelat-, -suberat und -azelainat und sebacate hingegen in der Reaktion von YCl₃ mit dem Ammoniumsalz der Säure. In Form kristalliner Feststoffe wurden Yttriumalkanodicarboxylate der allgemeinen Formel Y₂L₃,nH₂O mitn=3, 4, 6 bzw. 7 hergestellt. Ausgehend von den IR-Spektren konnte die Art der Koordinierung als COO^– y³⁺ festgestellt werden. Beim Erhitzen geben Ytrriummalonat, -succinat, -glutarat, azelainat und -sebazat ihr Kristallwasser ab, aus den anhydratierten Komplexen bildet sich anschliessend Y₂O₃, während Yttriumadipet, pimelat und -suberat einige Wassermoleküle verlieren und die monooder dihydratierten Formen sich dann zu Y₂O₃ zersetzen. Die Eigenschaften der untersuchten Komplexe variieren eindeutig in Abhängigkeit davon, ob sich in der Kette eine gerade oder ungerade Anzahl von Kohlenstoffatomen befindet.

     

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.

     

Thermal decomposition of rare earth pyromucates in air atmosphere

The conditions of thermal decomposition of Y, La and lanthanide (from Ce(III) to Lu) pyromucates have been studied. On heating, these complexes decompose in various ways: La, Pr, Nd and Sm pyromucates in four stages, Ce, Eu, Gd, Dy, Ho and Er pyromucates in three stages, and Tm, Yb, Lu and Y pyromucates in two stages, the oxides finally being formed. The hydrated complexes (from La to Er) lose crystallization water to form anhydrous salts. The anhydrous complexes of La, Pr, Nd and Sm decompose to oxides through the intermediate formation of unstable oxypyromucates and Ln₂O₂CO₃, whereas the anhydrous complexes of Ce(III), Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu decompose to the oxides through the intermediate formation of oxypyromucates. The temperatures of dehydration and oxide formation change periodically with increasing atomic number in the lanthanide series.

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Zusammenfassung Die Bedingungen der thermischen Zersetzung der Pyromucate von Y, La und den Lanthaniden (Ce(III) bis Lu) wurden untersucht. Beim Erhitzen zersetzen sich die Komplexe auf verschiedene Weise: die Pyromucate von La, Pr, Nd und Sm in 4 Schritten, die von Ce, Eu, Gd, Dy, Hod Er in 3 Schritten und die von Tm, Yb, Lu und Y in nur 2 Schritten. Endprodukte der Zersetzung sind die Oxide, Die hydratisierten Komplexe von La bis Er verlieren Kristallwasser unter Bildung der wasserfreien Salze. Die wasserfreien Komplexe von La, Pr, Nd und Sm zersetzen sich zu Oxiden über instabile Oxypyromucate und Ln₂O₂CO₃ als Zwischenprodukte, bei der Zersetzung der wasserfreien Komplexe von Ce(III), Eu, Gd, Dy, Ho, Er, Tm, Yb und Lu werden Oxypyromucate als Zwischenprodukte gebildet. Die Temperaturen der Dehydratisierung und Oxidbildung schwanken periodisch mit ansteigender Atomzahl in der Lanthanidenreihe.

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