X-ray,Thermal and Infrared Spectroscopic Studies on Potassium,Rubidium and Caesium Uranyl Oxalate Hydrates

M₂UO₂(C₂O₄)₂⋅nH₂O compounds (M=K, Rb and Cs)have been prepared and characterized by chemical and thermal analyses as well as by X-ray diffraction and infrared spectroscopy. X-ray powder data show that the compounds belong to an orthorhombic system. Thermal and infrared studies show that the compounds decompose to M₂UO₄ through the formation of alkali metal carbonate and UO₂ as intermediates. K₂UO₂(C₂O₄)₂⋅3H₂O, and Rb₂UO₂(C₂O₄)₂⋅2H₂O gave K₂UO₄, Rb₂UO₄ at 700 and 600°C respectively, while in the case of Cs₂UO₂(C₂O₄)₂⋅2H₂O, the intermediate products of decomposition reacted to yield Cs₂U₄O₁₃ at 1000°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

TG and DTA Evaluation of Cobalt Salts and Complexes Mixed with Activated Carbon

The thermal decomposition process of mixtures of CoC₂O₄⋅2H₂O (COD) or Co(HCOO)₂⋅2H₂O (CFD) or [Co(NH₃)₆]₂(C₂O₄)₃⋅4H₂O (HACOT) with activated carbon was studied with simultaneous TG–DTG–DTA measurements under non-isothermal conditions in argon and argon/oxygen admixtures. The results show that the thermal decomposition of the studied mixtures in Ar proceeds in the same manner. It begins with the salt decomposition to Co_met+CoO mixture followed by (T>680 K) the simultaneous reduction of CoO to Co_metand carbon degasification. The final product of the thermal decomposition of COD-C and CFD-C mixtures, identified by XRD, is β-Co. Cobalt contents determined in the final products fall in the range 71–78 mass%. The rest is amorphous residual carbon. In Ar/O₂ admixtures the end product is Co₃O₄ with ash admixture. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal Studies of Copper(II) Squarate Complexes of Diamines in the Solid State

CuL₂C₄O₄ [L=ethane-1,2-diamine (en)], CuL₂C₄O₄⋅2H₂O [L=N-methylethane-1,2-diamine (meen), N-ethylethane-1,2-diamine (eten),N-propylethane-1,2-diamine (pren), N-methyl-N’-ethylethane- 1,2-diamine (meeten) andpropane-1,2-diamine (pn)], CuL₂C₄O₄⋅0.5H₂O [L=N,N’-dimethylethane- 1,2-diamine (dmeen)], CuL₂C₄O₄⋅4H₂O [L=propane-1,2-diamine (pn)]and CuL₂C₄O₄⋅H₂O[L=2-methylpropane-1,2-diamine (ibn)] have been synthesized by the addition of respective diamine to finely powdered CuC₄O₄⋅2H₂O and their thermal studies have been carried out in the solid state. Cu(en)₂C₄O₄ upon heating loses one molecule of diamine with shar pcolour change yielding Cu(en)C₄O₄ which upon further heating transforms to unidentified products. All aquated-bis-diamine species [CuL₂C₄O₄⋅2H₂O, CuL₂C₄O₄⋅0.5H₂O and CuL₂C₄O₄⋅H₂O] upon heating undergo deaquation–anation reaction in the solid state showing thermochromism and transform to CuL₂C⁴O₄, which revert on exposure to humid atmosphere (RH ∼90%). All the squarato bis-diamine species, CuL₂C₄O₄, on further heating transform to unidentified products through the formation of CuLC₄O₄ as intermediates. The mono diamine species, have been isolated pyrolytically in the solid state and can be stored in a desiccator as well as in open atmosphere. They are proposed to be polymeric. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and Thermal Study of Magnesium Complexes with 8-hydroxyquinolinate Derivatives

Magnesium ion was reacted with 5,7-dibromo-, 5,7-dichloro-, 7-iodo-and 5-chloro-7-iodo-8-hydroxyquinoline, in acetone/ammonium hydroxide medium under constant stirring to obtain (I) Mg[(C₉H₄ONBr₂)₂]·2H₂O; (II) Mg[(C₉H₄ONCl₂)₂]·3H₂O; (III) Mg[(C₉H₅ONI)₂]·2H₂O and (IV)Mg[(C₉H₄ONICl)₂]·2.5H₂O complexes. The compounds were characterized by elemental analysis, IR spectra, ICP, TG-DTA and DSC. Through thermal decomposition residues were obtained and characterized, by X-ray diffractometry, as a mixture of hexagonal MgBr₂ and cubic MgO to the (I) compound at 850°C; cubic MgO to the (II), (III) and (IV) compounds at750, 800 and 700°C, respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

Hydrazinium Oxydiacetates and Oxydiacetate Dianion Complexes of Some Divalent Metals with Hydrazine

Hydrazinium oxydiacetate salts of formulae N₂H₅(Hoda)⋅H₂oda, N₂H₅(Hoda) and (N₂H₅)₂oda (H₂oda=oxydiacetic acid) and complexes of the types, M(oda)⋅2N₂H₄⋅xH₂O (where M=Co, Ni and Cd; x=0 for Co and Ni;x=1 for Cd) and Zn(oda)⋅N₂H₄⋅H₂O have been prepared and characterized by analytical, spectral, thermal and X-ray powder diffraction data. IR data document the existence of N₂H⁺ ₅ ion in the simple salts and the bidentate coordination of both hydrazine and dianion in the complexes. Complete decomposition of hydrazinium salts takes place via oxydiacetic acid intermediate. Cobalt and nickel complexes decompose in a single step, whereas zinc and cadmium complexes decompose through hydrazinate intermediates. However, all the metal complexes yield metal oxide as the final residue. Isomorphic nature of the cobalt and nickel complexes is evident from XRD data. This revised version was published online in August 2006 with corrections to the Cover Date.     

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.     

Solid Phase Synthesis, Characterization of Hexamethylenetetramine Complexes of Antimony and Bismuth Trichloride

New hexamethylenetetramine complexes of antimony and bismuth trichloride were synthesized through a solid phase reaction of hexamethylenetetramine and antimony or bismuth trichloride. The formula of the complex is MCl₃(C₆H₁₂N₄)₂⋅H₂O (M=Sb, Bi).The crystal structure of the complexes belongs to monoclinic system and the lattice parameters: a=1.249 nm, b=1.4583 nm, c=1.6780 nm andβ=91.78° for SbCl₃(C₆H₁₂N₄)₂⋅H₂O and a=1.3250 nm, b=1.3889 nm, c=1.7449 nm and β=98.94° for BiCl₃(C₆H₁₂N₄)₂⋅H₂O. Far-infrared spectra reveal that the antimony or bismuth ion is coordinated by the nitrogen atom of the hexamethylenetetramine. The thermal analysis also demonstrates the complex formation between the antimony or bismuth ion and hexamethylenetetramine. The intermediate and final residues in the thermal decomposition process have been analyzed to check the pyrolysis reaction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal Decomposition of Cu(II) Complexes with 2-Chloro- and 2,6-Dichlorobenzoic Acid and Imidazole

The reaction products of Cu(II) 2-chlorobenzoate and the imidazole (1), and of Cu(II) 2,6-dichlorobenzoate and the imidazole (2) formulated as CuL’₂⋅2imd⋅2H₂O and CuL”₂⋅2imd⋅2H₂O (L’=C₇H₄ClO₂ ⁻, L”=C₇H₃Cl₂O₂ ⁻, imd=imidazole), were prepared and characterized by means of spectroscopic measurements and thermochemical properties. The blue (1) and green (2) complexes were obtained as solids with a 1:2:2 molar ratio of metal to carboxylate ligand to imidazole. When heated at a heating rate of 10 K min⁻¹ the hydrated complexes, (1) and (2), lose some of the crystallization water molecules and then decompose to gaseous products. This revised version was published online in August 2006 with corrections to the Cover Date.     

Darstellung von Bariumwolframat durch tribochemische Reaktion

Stoichiometric mixture of powders BaO/WO₃, Ba(OH)₂/WO₃, BaCO₃/WO₃, BaSO₄/WO₃ are grinded in a vibrating mill. IR spectra, X-rays diffractions, DTA, TGA. investigation of conductivity and solubility show that

• – 100% of BaWO₄ arise from BaO/WO₃ after grinding 5 hours in a vibrating mill,
• – the degree of interaction decreases in the sequence BaO? Ba(OH)₂? BaCO₃? BaSO₄ corresponding to Δ_R G °,
• – no tribochemical reaction BaSO₄/WO₃ occurs.

     

Study of the Dehydration/Rehydration of Ammonium Tris-Oxalato Aluminate(III) (NH4)3Al(C2O4)3⋅3H2O at Controlled Atmosphere

The study of the dehydration/rehydration of ammonium tris-oxalato aluminate(III) (NH₄)₃Al(C₂O₄)₃⋅3H₂O in flowing dinitrogen saturated with water vapor at room temperature, using thermogravimetric analysis and X-ray diffraction techniques, allowed the determination of the temperature stability domains of (NH₄)₃Al(C₂O₄)₃⋅3H₂O, (NH₄)₃Al(C₂O₄)₃⋅2H₂O and the anhydrous salt. The X-ray powder diffraction profiles are reported for each of the three phases. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal Decomposition of Barium Dioxodiaquaperoxyoxalato Uranate(VI) Hydrate

Barium dioxodiaquaperoxyoxalatouranate was obtained by reaction of uranyl nitrate with oxalic acid and then hydrogen peroxide in the presence of barium ion. The complex was subjected to chemical analysis. The thermal decomposition behaviour of the complex was studied using TG, DTG and DTA techniques. The solid complex salt and the intermediate product of its thermal decomposition were characterized using IR absorption and X-ray diffraction spectra. Based on data from these physico-chemical investigations the structural formula of the complex was proposed as Ba[UO₂(O₂)(C₂O₄)(H₂O)₂]⋅H₂O. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal studies on nickel(II) 4-iodopyrazole complexes

This work describes the synthesis, IR and UV-Vis spectroscopic characterization as well the thermal behavior of the [NiCl₂(HIPz)₄]⋅C₃H₆O (1), [Ni(H₂O)₂(HIPz)₄](NO₃)₂ (2), [Ni(NCS)₂(HIPz)₄] (3) and [Ni(N₃)₂(HIPz)₄] (4) (HIPz=4-iodopyrazole) pyrazolyl complexes. TG experiments reveal that the compounds 1–4 undergo thermal decomposition in three or four mass loss steps yielding NiO as final residue, which was identified by X-ray powder diffraction.     

Thermal Decomposition Studies of Mixed Rare Earth Hydrogen Selenite Crystals

Mixed rare earth hydrogen selenite crystals, neodymium praseodymium hydrogen selenite (Nd_xPr_1−x(HSeO₃)(SeO₃)⋅2H₂O), Neodymium samarium hydrogen selenite (Nd_xSm_1−x(HSeO₃)(SeO₃)⋅2H₂O) and praseodymium samarium hydrogen selenite (Pr_xSm_1−x(HSeO₃)(SeO₃)⋅2H₂O) were prepared by gel diffusion technique. Simultaneous thermogravimetric and differential thermal analysis were carried out on the grown crystals. Decomposition is observed to occurs in six steps, which gives the evidence of successive losses of H₂O and SeO₂. The final product due to decomposition is a mixed rare earth oxides. FT-IR spectrum of the crystal samples heated at different temperatures complemented to the TG-DTA results. This revised version was published online in July 2006 with corrections to the Cover Date.     

Kinetic Analysis of Dissociation of Smithsonite from a Set of Non-isothermal Data Obtained at Different Heating Rates

The heats of hydration reactions for MgCl₂⋅4H₂O and MgCl₂⋅2H₂O include two parts, reaction enthalpy and adsorption heat of aqueous vapor on the surfaces of magnesium chloride hydrates. The hydration heat for the reactions MgCl₂⋅4H₂O+2H₂O→MgCl₂⋅6H₂O and MgCl₂⋅2H₂O+2H₂O→MgCl₂⋅4H₂O, measured by DSC-111, is –30.36 and –133.94 kJ mol^–1,respectively. The adsorption heat of these hydration processes, measured by head-on chromatography method, is –13.06 and –16.11 kJ mol^–1, respectively. The molar enthalpy change for the above two reactions is –16.64 and –118.09 kJ mol^–1, respectively. The comparison between the experimental data and the theoretical values for these hydration processes indicates that the results obtained in this study are quite reliable. This revised version was published online in July 2006 with corrections to the Cover Date.     

Some dn Metal Complexes with 4,4'-bipyridine and Trichloroacetates. Preparation,characterization and thermal properties

The new mixed ligand complexes with formulae Co(4-bpy)₂L₂⋅2H₂O (I), Cu(4-bpy)₂L₂⋅H₂O (II) and Cd(4-bpy)L₂⋅H₂O (III) (4-bpy=4,4'-bipyridine, L=CCl₃COO^–) were prepared. Analysis of the IR spectra indicate that 4-bpy is coordinated with metal ions and carboxylates groups bond as bidentate chelating ligands. The electronic spectra are in accordance with pseudo-octahedral environment around the central metal ion in the Co(II) and Cu(II) complexes. The thermal decomposition of the synthesized complexes was studied in air. A coupled TG-MS system was used to analyse the principal volatile thermal decomposition products of Co(II) and Cu(II) complexes. Corresponding metal oxides were identified as a final product of pyrolysis with intermediate formation of metal chlorides. This revised version was published online in July 2006 with corrections to the Cover Date.     

Direkte Bestimmung der Additivelemente Ca, Ba und Zn in Schmier?len

Zusammenfassung Lösungen von CaCl₂ · 2 H₂O, BaCl₂ · 2 H₂O und Zn(CH₃CO₂)₂ · 2 H₂O in Dimethylsulfoxid lassen sich anstelle metallorganischer Verbindungen als Standards zur direkten Bestimmung der Additivelemente Ca, Ba und Zn in Schmierölen mittels Atomabsorptionsspektroskopie verwenden. In 10 verschiedenen Ölen wurden die Additive bestimmt. Die mit Atomabsorption erhaltenen Meßergebnisse weichen von den naßchemisch ermittelten um maximal 5% ab.

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Direct determination of the additive elements Ca, Ba and Zn in lubricating oilsSolutions of inorganic salts in dimethyl sulphoxide as standards in atomic absorption spectroscopy

For the determination of the additive elements Ca, Ba and Zn in oils by atomic absorption spectroscopy, solutions of CaCl₂ · 2 H₂O, BaCl₂ · 2 H₂O and Zn(CH₃CO₂)₂ · 2 H₂O in dimethyl sulphoxide can be used as standards instead of metallorganic compounds. The additives in 10 different oil samples have been determined. The results obtained by atomic absorption differ from those gained by conventional analytical methods by 5% at most.

     

Zur Kenntnis der Hydrate des Bariumchlorids. Röntgenographische,thermoanalytische, Raman- und IR-spektroskopische Untersuchungen

Hydrates of Barium Chloride. X-ray, Thermoanalytical, Raman, and I.R. Data In the system BaCl₂? H₂O the hydrates BaCl₂ · 2 H₂O, BaCl₂ · 1 H₂O, BaCl₂ · 1/2 H₂O, and BaCl₂ · uH₂O were obtained. X-ray powder data, i.r. and Raman spectra, as well as thermoanalytical measurements (TG, DTA) are reported. BaCl₂ · 1 H₂O and BaCl₂ · 1/2 H₂O, which are both isotype with the corresponding hydrates of SrCl₂, were prepared by dehydration of BaCl₂ · 2 H₂O or by back hydration of anhydrous BaCl₂ with the calculated amounts of water. BaCl₂ · uH₂O (u ≈? 1) is formed as the primary product by the reaction of anhydrous BaCl₂ with water vapour at room temperature. Preparation methods of salt hydrates by controlled back hydration of the anhydrous salts are reported.     

A simple solution route to control synthesis of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanomaterials at low temperature and their magnetic properties

A series of nanostructured iron compounds including cubic Fe₃O₄ and orthorhombic FeOOH were synthesized via a facile low temperature (in the range of 60?100°C) solution method. In the whole process, the interaction between FeCl₂·4H₂O and methenamine (C₆H₁₂N₄) was carried out through a reflux device under different reaction conditions such as temperature, solvent, and duration. The samples were detected by XRD, TEM, SAED, physical property measurement system, and Mössbauer spectroscopy, separately. The experiments showed that magnetic mixture nanoparticles had flake and rod morphologies, and cubic Fe₃O₄ took on grain nanostructure. Magnetism measurements indicated that the saturated magnetization of the as-obtained magnetic mixture was lower than that of the cubic magnetite. Mössbauer spectroscopy testified the sample consisting of cubic magnetite rather than γ-Fe₂O₃. In addition, a possible growth mechanism of cubic magnetic nanoparticles under different conditions was discussed.     

Reaction of a naphthalene complex C10H8Yb(THF)2 with cyclopentadienyl-substituted alcohols and amines as a convenient synthetic route to the half-sandwich complexes of divalent ytterbium

The reactions of ytterbium naphthalene complex C₁₀H₈Yb(THF)₂ with 2-cyclopentadienylethanol, 1-cyclopentadienylpropan-2-ol, 3-cyclopentadienyl-1-butoxypropan-2-ol, and cyclopentadienyldimethylsilyl-tert-butylamine were studied. The bivalent ytterbium complexes with chelate bifunctional cyclopentadienyl ligands [(η⁵−C₅H₅)CH₂CH₂(η¹−O)]Yb(THF), [(η⁵−C₅H₅)CH₂CH₂(η¹−O)]Yb(DME). [(η⁵−C₅H₅)CH₂CH(Me)(η¹−O)]Yb(THF), [(η⁵−C₅H₅)CH₂CH(CH₂OC₄H₉)(η¹−O)]Yb(THF), and [(η⁵−C₅H₅)SiMe₂(η¹−N(Bu¹))]Yb(THF) were obtained and characterized. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 742–745, April, 2000.     

Fullerene complexes with bis(η6-hexamethylbenzene)chromium, hexamethylbenzene, and hexaethylbenzene

The [60]fulleride of bis(η-hexamethylbenzene)chromium(I) [(η⁶-C₆Me₆)₂Cr]^⋅+[C₆₀]^⋅−, and the complexes C₆₀·C₆Me₆ and C₆₀·C₆Et₆ were synthesized. Thermal decomposition of [(η⁶-C₆Me₆)₂Cr]^⋅+[C₆₀]^⋅− was studied. The molecular structures of C₆₀·C₆Me₆ and C₆₀·C₆Et₆ were determined. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 220—224, February, 2006.