Gases Released During the Conversion of NH4Zr2(PO4)3 to HZr2(PO4)3

Gases released during the conversion of NH₄Zr₂(PO₄)₃ to HZr₂(PO₄)₃ were identified using an apparatus in which gases released from a sample placed in a thermogravimetric analyzer were directly introduced to a gas cell of an IR spectrometer. Such acidic gases as N₂O and NO were detected besides the basic NH₃ gas, and their formation mechanism was discussed.This revised version was published online in November 2005 with corrections to the Cover Date.     

Host-Guest Interactions between Calixarenes and Cp(2)NbCl(2)

The possible inclusion complexes of Cp₂NbCl₂ into calixarenes hosts have been investigated. The existence of a true inclusion complex in the solid state was confirmed by a combination of NMR, ab-initio calculations, thermogravimetric analysis, FTIR, Raman and PXRD. Ab-initio calculations, ¹H NMR solution and solid state ¹³C CP-MAS NMR results demonstrated that p-sulfonic calix[6]arene does form an inclusion complex with Cp₂NbCl₂. Raman spectroscopy showed, for the inclusion compound of p-sulfonic calix[6]arene-Cp₂NbCl₂, a band between 500 and 850 cm⁻¹ characteristic of Nb-O vibration. This result suggests that Nb(V) may engage in coordination with the oxygen of the sulfonate group, as part of the host-guest interaction. However, it is important to mention that the niobocene dichloride (Cp₂NbCl₂) dissolves in water and undergoes oxidation and hydrolysis processes to yield Cp₂NbCl₂(OH) species. For that reason this band does not exclude that the Nb-O band belongs to Cp₂NbCl₂(OH). Solid State ¹³C CP-MAS NMR and solution ¹H NMR spectroscopies together with ab-initio results showed that Cp₂NbCl₂ is included in the p-sulfonic calix[6]arene cavity, with both Cp rings inside the cavity. In contrast, the solution ¹H NMR results demonstrated that calix[6]arene does not form inclusion complex with Cp₂NbCl₂ in CDCl₃ solution. Cp₂NbCl₂ is not included in the calix[6]arene cavity, possibly due to the lack of sulfonate heads which promote Nb-O interactions and assist the inclusion of Cp₂NbCl₂ into the cavity.     

Low-temperature heat capacity and standard enthalpy of formation of neodymium glycine perchlorate complex [Nd2(Gly)6(H2O)4](ClO4)6·5H2O

Rare-earth perchlorate complex coordinated with glycine [Nd₂(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O was synthesized and its structure was characterized by using thermogravimetric analysis (TG), differential thermal analysis (DTA), chemical analysis and elementary analysis. Its purity was 99.90%. Heat capacity measurement was carried out with a high-precision fully-automatic adiabatic calorimeter over the temperature range from 78 to 369 K. A solid-solid phase transformation peak was observed at 256.97 K, with the enthalpy and entropy of the phase transformation process are 4.438 kJ mol⁻¹ and 17.270 J K⁻¹ mol⁻¹, respectively. There is a big dehydrated peak appears at 330 K, its decomposition temperature, decomposition enthalpy and entropy are 320.606 K, 41.364 kJ mol⁻¹ and 129.018 J K⁻¹ mol⁻¹, respectively. The polynomial equations of heat capacity of this compound in different temperature ranges have been fitted. The standard enthalpy of formation was determined to be −8023.002 kJ mol⁻¹ with isoperibol reaction calorimeter at 298.15 K.     

亚稳态MInS2(M=Ag,Cu)花状微米球的热分解法合成及其生长机理

采用热分解法制备了三维的亚稳态正交相AgInS_2和六方相CuInS_2花状微米球。通过X射线衍射(XRD),场发射扫描电子显微镜(FESEM)等对样品进行表征,对AgInS_2的光催化性能进行了评估,并借助于热重-差热分析(TG-DTA)等手段研究了亚稳态正交相AgInS_2和六方相CuInS_2花状微米球的生长机理。实验结果表明,反应温度和反应物中金属离子的投料比对生成纯相的MIn S2均有影响,而AgInS_2花状微米球能在可见光下较好地催化降解亚甲基蓝。     

Pyrolysis study of sol—gel derived TiO2 powders: Part III. TiO2-anatase prepared by reacting titanium(IV) isopropoxide with acetic acid

A homogeneous TiO₂ gel was obtained by hydrolysing titanium(IV) isopropoxide that was previously modified by reaction with acetic acid. The so stabilized precursor was hydrolysed under strong acidic medium (pH=0 by HCl). Dried TiO₂ powders were characterized by FT-IR, XRD, N₂ adsorption analyses, coupled thermogravimetric (TG) gas chromatographic (GC) and `mass spectrometric (MS) analyses. A semiquantitative analysis of the main evolved chemical species allowed to depict both the chemical rearrangements occurring in the TiO₂ matrix during pyrolysis and the chemical composition of the initial gel.This revised version was published online in November 2005 with corrections to the Cover Date.     

Crystal structure of Li2Cu3(SeO3)2(SeO4)2

Summary Single crystal X-ray data of the hydrothermally grown new phase Li₂Cu₃(SeO₃)₂(SeO₄)₂ were measured with a four-circle diffractometer up to sin /=0.81 Å^–1 [I2/a,Z=4,V=1175.5 ų,a=16.293(6),b=5.007(2),c=14.448(6) Å, = 94.21(1)°]. The structure was determined by direct and Fourier methods and refined toR=0.034,R _w =0.027 for 2 086 independent reflections.Cu(1)^[4+1]O₅ forms a tetragonal pyramid, Cu(2)^{[4 + 2]}O₆ is a strongly elongated octahedron. The Li atom is surrounded by four O atoms forming a distorted tetrahedron. Se(IV)O₃ and Se(VI)O₄ groups are in accordance to literature, mean Se-O bond lengths are 1.714 and 1.644 Å.

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Die Kristallstruktur von Li₂Cu₃(SeO₃)₂(SeO₄)₂

Zusammenfassung Einkristall-Röntgendaten der hydrothermal gezüchteten neuen Phase Li₂Cu₃(SeO₃)₂(SeO₄)₂ wurden mit einem Vierkreisdiffraktometer im Bereich bis zu sin /=0.81 Å^–1 gemessen [I2/a,Z=4,V=1175.5 ų,a=16.293(6),b=5.007(2),c=14.448(6) Å, =94.21(1)°]. Die Kristallstruktur wurde mittels direkter und Fourier-Methoden bestimmt und für 2 086 unabhängige Reflexe zuR=0.034,R _w =0.027 verfeinert.Cu(1)^[4+1]O₅ bildet eine tetragonale Pyramide, Cu(2)^[4+2]O₆ ist ein stark verlängertes Oktaeder. Das Li-Atom ist von vier O-Atomen in Gestalt eines verzerrten Tetraeders umgeben. Die Se(IV)O₃-und Se(VI)O₄-Gruppen entsprechen der Literatur, die mittleren Se-O-Abstände betragen 1.714 und 1.644 Å.

     

Preparation, characterization, and infrared emissivity property of optically active polyurethane/TiO2/SiO2 multilayered microspheres

Optically active polyurethane/titania/silica (LPU/TiO₂/SiO₂) multilayered core–shell composite microspheres were prepared by the combination of titania deposition on the surface of silica spheres and subsequent polymer grafting. LPU/TiO₂/SiO₂ was characterized by FT-IR, UV–vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), SEM and TEM, and the infrared emissivity value (8–14 μm) was investigated in addition. The results indicated that titania and polyurethane had been successfully coated onto the surfaces of silica microspheres. LPU/TiO₂/SiO₂ exhibited clearly multilayered core–shell construction. The infrared emissivity values reduced along with the increase of covering layers thus proved that the interfacial interactions had direct influence on the infrared emissivity. Besides, LPU/TiO₂/SiO₂ multilayered microspheres based on the optically active polyurethane took advantages of the orderly secondary structure and strengthened interfacial synergistic actions. Consequently, it possessed the lowest infrared emissivity value.     

Die Kristallstruktur von Dikalium-trikobalt(II)-dihydroxid-trisulfat-dihydrat,K2Co3(OH)2(SO4)3·2H2O

Crystals of K₂Co₃(OH)₂(SO₄)₃·2H₂O were synthesized under hydrothermal conditions. The crystal structure [a=17.945 (4) Å,b=7.557 (2) Å,c=9.760 (3) Å, space group Cmc2₁,Z=4] was determined by direct methods and refined with single crystal X-ray data. The H atoms were located byFourier syntheses. Their structural parameters were refined, too. The finalR-values areR=0.025 andR _w =0.028 (w=1/) for 612 reflections withF ₀>3 (F ₀). Both Co(II) atoms are octahedral six coordinated and form zigzag chains running parallel [001]. These chains are connected via sulfate groups to built up sheets parallel (100). The KO₉ polyhedron and one of the four hydrogen bonds link these sheets.

     

Investigation on The Thermal Properties of Fe2O(SO4)2. Part II

Fe₂O(SO₄)₂ is a secondary product of the decomposition of FeSO₄⋅H₂O. Part I of this study presents results on the synthesis of Fe₂O(SO₄)₂ in gaseous environment containing either low or high concentration of oxygen. In this paper the existence of differences between the structures of Fe₂O(SO₄)₂ and Fe₂(SO₄)₃ is proved on the basis of a detailed thermal study of Fe₂O(SO₄)₂ upon dynamic heating (differential thermal analysis) and upon isothermal heating (thermal-analytic balance) in various gaseous environments as well as by presenting kinetic data on the processes of decomposition of both compounds. This revised version was published online in July 2006 with corrections to the Cover Date.     

A comparison of the role of boehmite (AlOOH) and alumina (Al2O3) in the thermal stability and flammability of poly(methyl methacrylate)

In this paper, a comparison of the role of boehmite (AlOOH) and alumina (Al₂O₃) in the thermal stability and flame retardant behaviour of poly(methyl methacrylate) (PMMA) is presented. PMMA–AlOOH and PMMA–Al₂O₃ nanocomposites were prepared by melt blending with different filler contents. These nanocomposites were studied by thermogravimetric analysis (TGA) and cone calorimetry. In the presence of the filler (alumina or boehmite), the thermal stability of the polymer appeared to be significantly improved. An increase of the decomposition temperature of between about 19 and 35 °C was demonstrated by TGA. Cone calorimeter measurements showed that the peak of heat release rate is lowered in the presence of AlOOH or Al₂O₃ in comparison to pure PMMA and that this decrease is higher when the filler content increases. When loading rate is higher (15 wt%), a significant improvement in fire resistance of PMMA was observed in both systems but with two different modes of action.     

The effect of B2O3 addition on the crystallization of amorphous TiO2-ZrO2 mixed oxide

The effect of B₂O₃ addition on the crystallization of amorphous TiO₂-ZrO₂ mixed oxide was investigated by X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG/DTA). TiO₂-ZrO₂ mixed oxide was prepared by co-precipitation method with aqueous ammonia as the precipitation reagent. Boric acid was used as a source of boria, and boria contents varied from 2 to 20 wt%. The results indicate that the addition of small amount of boria (<8 wt%) hinders the crystallization of amorphous TiO₂-ZrO₂ into a crystalline ZrTiO₄ compound, while a larger amount of boria (?8 wt%) promotes the crystallization process. FT-IR spectroscopy and ¹¹B MAS NMR results show that tetrahedral borate species predominate at low boria loading, and trigonal borate species increase with increasing boria loading. Thus it is concluded that highly dispersed tetrahedral BO₄ units delay, while a build-up of trigonal BO₃ promote, the crystallization of amorphous TiO₂-ZrO₂ to form ZrTiO₄ crystals.     

Die Kristallstruktur von Cu7(OH)6(TeO3)2(SO4)2

The crystal structure of the new phase Cu₇(OH)₆(TeO₃)₂(SO₄)₂ [a=7.389 (1),b=7.638 (1),c=7.662 (2) Å, =75.17 (1), =75.90 (1), =84.19 (1)°;Z=1] was determined by direct methods andFourier summations from X-ray intensities, and was refined in space group P -C _i ¹ toR=0.039. As usual, the Cu(II) atoms are coordinated to four O atoms forming approximately a square with average Cu-O=1.96 (3) Å; one or two more distant O neighbours complete the coordination. The shape of the TeO₃ group is a rather clear-cut trigonal pyramid. A disorder was found for the SO₄ tetrahedra. The compound was synthesized under hydrothermal conditions [500 (10) K, saturation vapour pressure].

Herrn Prof. Dr.K. Komarek zum 60. Geburtstag gewidmet.     

Synthesis,characterization and luminescence of the tetranuclear gold cluster: [Au4{7,8-(PPh2)2-7,8-C2B9H10}2(PPh3)2]

A tetranuclear gold cluster has been synthesized by the reaction of [Au(PPh₃)NO₃] with the closo carborane diphosphine 1,2-(PPh₂)₂-1,2-C₂B₁₀H₁₀ in THF, and characterized by elemental analysis, FT-IR, ¹H and ¹³C?NMR spectroscopy and X-ray structure determination. The cluster crystallizes in the triclinic Pī, a?=?15.118(8)?Å, b?=?16.057(9)?Å, c?=?24.284(13)?Å, α?=?80.822(9)°, β?=?79.624(8)°, γ?=?81.938(8)°, Z?=?2, R ₁?=?0.0626, wR ₂?=?0.1894. A single crystal structure determination showed that four gold atoms form a tetrahedral framework. Among these four gold atoms, two were chelated by two nido carborane diphosphine [7,8-(PPh₂)₂-7,8-C₂B₉H₁₀]^? anions coming from the degradation of the initial closo ligand 1,2-(PPh₂)₂-1,2-C₂B₁₀H₁₀, while the other two were ligated to two PPh₃ groups. The luminescence of this cluster was also investigated in dichloromethane solution at room temperature.     

Co取代的六铁酸盐在N2O催化分解反应中的应用

采用溶胶-凝胶法制备了Co取代的Ba₂Mg_2-xCo_xFe₁₂O₂₂(x=0.0~2.0)催化剂,并考察了其在高浓度N₂O(30vol%)分解反应中的催化活性.结果表明,Co的取代显著提高了Ba₂Mg₂Fe₁₂O₂₂催化剂活性,当x=2时,N₂O的完全分解温度从1123K降至973K;提高催化剂焙烧温度会导致其表面积降低,进而降低其催化活性;但采用微波加热则能显著提高催化剂活性.     

亚稳态MInS2(M=Ag，Cu)花状微米球的热分解法合成及其生长机理

采用热分解法制备了三维的亚稳态正交相AgInS₂和六方相CuInS₂花状微米球。通过X射线衍射（XRD）,场发射扫描电子显微镜（FESEM）等对样品进行表征,对AgInS₂的光催化性能进行了评估,并借助于热重分析（TG-DTA）等手段研究了亚稳态正交相AgInS₂和六方相CuInS₂花状微米球的生长机理。实验结果表明,反应温度和反应物中金属离子的投料比对生成纯相的MInS₂均有影响,而AgInS₂花状微米球能在可见光下较好地催化降解亚甲基蓝。     

Synthesis and thermal investigation of Na2Cd(SO4)2·2H2O

The synthesis and thermal decomposition of Na₂(SO₄)₂·2H₂O in both air and nitrogen are described. The synthesis was performed by two different procedures, but in both cases the same product was obtained, corresponding to the general formula given above. The crystals obtained were investigated by methods of X-ray powder diffraction, and chemical and thermal analysis. The differences in thermal decomposition in air and nitrogen are discussed.     

PbCu3(OH)(NO3)(SeO3)3·1/2H2O und Pb2Cu3O2(NO3)2(SeO3)2: Synthese und Kristallstrukturuntersuchung

Crystals of PbCu₃(OH)(NO₃)(SeO₃)₃·1/2H₂O [a=7.761(3)Å,b=9.478(4)Å,c=9.514(4)Å, =66.94(2)°, =69.83(2)°, =81.83(2)°, space group P ,Z=2] and Pb₂Cu₃O₂(NO₃)₂(SeO₃)₂ [a=5.884(2)Å,b=12.186(3)Å,c=19.371(4)Å, space group Cmc2₁,Z=4] were synthesized under hydrothermal conditions. Their crystal structures were refined with three-dimensional X-ray data toR _w=0.033 resp. 0.055. In PbCu₃(OH)(NO₃)(SeO₃)₃·1/2H₂O the Cu atoms are [4+1] and [4+2] coordinated and via SeO₃ groups a three-dimensional atomic arrangement is built up. In Pb₂Cu₃O₂(NO₃)₂(SeO₃)₂ there are sheets, which are connected only via Pb-O bonds ranging from 2.98 Å to 3.16 Å.

     

Replacement of the Common Chromium Source CrCl3(thf)3 with Well-Defined [CrCl2(μ-Cl)(thf)2]2

CrCl₃(thf)₃ is a common starting material in the synthesis of organometallic and coordination compounds of Cr. Deposited as an irregular solid with no possibility of recrystallization, it is not a purity guaranteed chemical, causing problems in some cases. In this work, we disclose a well-defined form of the THF adduct of CrCl₃ ([CrCl₂(μ-Cl)(thf)₂]₂), a crystalline solid, that enables structure determination by X-ray crystallography. The EA data and XRD pattern of the bulk agreed with the revealed structure. Moreover, its preparation procedure is facile: evacuation of CrCl₃·6H₂O at 100 °C, treatment with 6 equivalents of Me₃SiCl in a minimal amount of THF, and crystallization from CH₂Cl₂. The ethylene tetramerization catalyst [iPrN{P(C₆H₄-p-Si(nBu)₃)₂}₂CrCl₂]⁺[B(C₆F₅)₄]⁻ prepared using well-defined [CrCl₂(μ-Cl)(thf)₂]₂ as a starting material exhibited a reliably high activity (6600 kg/g-Cr/h; 1-octene selectivity at 40 °C, 75%), while that of the one prepared using the impure CrCl₃(thf)₃ was inconsistent and relatively low (~3000 kg/g-Cr/h). By using well-defined [CrCl₂(μ-Cl)(thf)₂]₂ as a Cr source, single crystals of [(CH₃CN)₄CrCl₂]⁺[B(C₆F₅)₄]⁻ and [{Et(Cl)Al(N(iPr)₂)₂}Cr(μ-Cl)]₂ were obtained, allowing structure determination by X-ray crystallography, which had been unsuccessful when the previously known CrCl₃(thf)₃ was used as the Cr source.     

Thermal decomposition of Me3SnO2PCl2, Me2Sn(O2PCl2)2 and Ph3SnO2PCl2

TG and DTA studies on Me₃SnO₂PCl₂, Me₂Sn(O₂PCl₂)₂ and Ph₃SnO₂PCl₂ were carried out under dynamic argon atmosphere. The results show that the decomposition proceeds in different stages leading to the formation of Sn₃(PO₄)₂ as a stable product. This compound was characterized by IR spectroscopy. Decomposition schemes involving reductive elimination reactions were proposed.     

Molar heat capacity and thermodynamic properties of crystalline Ho(Asp)Cl<Subscript>2</Subscript>·6H<Subscript>2</Subscript>O

The molar heat capacity, C _p,m, of a complex of holmium chloride coordinated with L-aspartic acid, Ho(Asp)Cl₂·6H₂O, was measured from 80 to 397 K with an automated adiabatic calorimeter. The thermodynamic functions H _T-H _298.15 and S _T-S _298.15 were derived from 80 to 395 K with temperature interval of 5 K. The thermal stability of the complex was investigated by differential scanning calorimeter (DSC) and thermogravimetric (TG) technique, and the mechanism of thermal decomposing of the complex was determined based on the structure and the thermal analysis experiment.