Phase evolution of a barium tin 1,2-ethanediolato complex to barium stannate during thermal decomposition

The thermal behaviour of [Ba(C₂H₆O₂)₄][Sn(C₂H₄O₂)₃] used as a BaSnO₃ precursor, and its phase evolution during thermal decomposition are described. The initially formed transient barium tin oxycarbonate phase disintegrates into BaCO₃ and SnO₂, reacting subsequently to BaSnO₃. The existence of the intermediate oxycarbonate phase is evidenced by Fourier transformed infrared (FT-IR), X-ray powder diffraction (XRD) and electron energy loss spectroscopy (EELS (ELNES)) investigations.     

Kinetics of thermal decomposition of barium zirconyl oxalate

Kinetics of the thermal decomposition of anhydrous barium zirconyl oxalate and a carbonate intermediate have been studied. Decomposition of the anhydrous oxalate, though it could be explained based on a contracting-cube model, is quite complex. Kinetics of decomposition of the intermediate carbonate Ba₂Zr₂O₅CO₃ is greatly influenced by thermal effects during its formation. (-t) curves are sigmoidal and obey a power law equation followed by first order decay. Presence of carbon in the vacuum-prepared carbonate has a strong deactivating effect. Decomposition of the carbonate is accompanied by growth in particle size of the product barium zirconate.

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Die Kinetik der thermischen Zersetzung von Barium-zirkonyl-oxalat

Zusammenfassung Es wurde die thermische Zersetzung von wasserfreiem Barium-zirkonyl-oxalat und dem intermediären Karbonat untersucht. Die Zersetzung des wasserfreien Oxalates ist — obwohl über das contracting-cube-Modell erklärbar — sehr komplex. Die Kinetik der Zersetzung des intermediären Karbonates Ba₂Zr₂O₅CO₃ ist stark von den thermischen Effekten während seiner Bildung abhängig. Die (-t)-Kurven gehorchen einem exponentiellen Gesetz, gefolgt von einem Zerfall erster Ordnung. Die Gegenwart von Kohlenstoff im Karbonat hat einen starken desaktivierenden Effekt. Die Zersetzung des Karbonats wird von einem Wachstum der Partikelgröße des Produktes (Bariumzirkonat) begleitet.

     

Synthesis, crystal structure and thermal decomposition of a new copper propionate [Cu(CH3CH2COO)2]·2H2O

A new copper propionate complex was synthesised and characterized for application as precursor for CuO based oxide thin films deposition. The FT-IR and X-ray diffraction analyses have revealed the formation of a cooper propionate complex [Cu(CH₃CH₂COO)₂]·2H₂O. The crystal and molecular structure of a new copper propionate complex was determined by XRD on the copper propionate single crystal. The copper propionate complex has a binuclear structure, connected by bridging bidentate carboxylates groups and a Cu?Cu bond of 2.6 Å. The thermal decomposition of copper propionate has been investigated by thermal analysis using thermogravimetric (TG) and differential thermal analysis (DTA), differential thermal analysis coupled with quadrupole mass spectrometry-QMS, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) techniques. TG and XRD data indicate the reduction of Cu(II)-Cu(I,0) during the decomposition of copper propionate.     

Synthesis, crystal structure and thermal decomposition of a novel praseodymium supermolecular complex

A novel complex, [Pr(5-nip)(phen)(NO3)(DMF)] (5-nip: 5-nitroisophthalic acid; phen: 1,10-phenanthroline, DMF: N,N-dimethylformamide), was prepared and characterized by single crystal X-ray diffraction, elemental analysis, IR spectrum and DTG-DSC techniques. The results show that the crystal is monoclinic, space group P2(1)/n with a=11.0876(6) Å, b=12.8739(7) Å, c=16.9994(8) Å; β=91.193(4)°, Z=4, D _c=1.822 Mg m^–3, F(000)=1320. Each Pr(III) ion is nine-coordinated by one chelating bidentate and two monodentate bridging carboxylate groups, one chelating bidentate nitryl group, one DMF molecule and one 1,10-phenanthroline molecule. The complex is constructed with one-dimensional ribbons featuring dinuclear units and the one-dimensional ribbons are further assembled into two-dimensional networks by strong π–π stacking interactions. The complex has high stability up to 500°C. The enthalpy change of formation of the compound in DMF was measured using an RD496-III type microcalorimeter with the value of –9.214±0.173 kJ mol^–1.     

Preparation, crystal structure and thermal expansion of a new bismuth barium borate, BaBi2B4O10

Single crystals of a new compound, BaBi₂B₄O₁₀ were grown by cooling a melt with the stoichiometric composition. The crystal structure of the compound has been solved by direct methods and refined to R₁=0.049 (wR=0.113) on the basis of 1813 unique observed reflections (|F_o|>4σ|F_o|). It is monoclinic, space group P2₁/c, a=10.150(2), b=6. 362(1), c=12.485(2) Å, β=102.87(1)^o, V=786.0(2) Å³, Z=4. The structure is based upon anionic thick layers that are parallel to (001). The layers can be described as built from alternating novel borate [B₄O₁₀]⁸⁻_∞ chains and bismuthate [Bi₂O₅]⁴⁻_∞ chains extended along b-axis. The borate chains are composed of [B₃O₈]⁷⁻ triborate groups of three tetrahedra and single triangles with a [BO₂]⁻ radical. The borate chains are interleaved along the c-axis with rows of the Ba²⁺ cations so that the Ba atoms are located within the layers. The layers are connected by two nonequivalent Ba-O bonds as well as by two equivalent Bi-O bonds with bond valences in the range of 0.2-0.3 v.u.Thermal expansion of BaBi₂B₄O₁₀ studied by high-temperature X-ray powder diffraction in the temperature range of 20-700 °C (temperature step 30-35 °C) is highly anisotropic. While the b and c unit-cell parameters increase almost linearly on heating, temperature dependencies of a parameter and β monoclinic angle show nonlinear behavior. As a result, on heating orientation of thermal expansion tensor changes, and bulk thermal expansion increases from 20×10⁻⁶ °C⁻¹ at the first heating stage up to 57×10⁻⁶ °C⁻¹ at 700 °C that can be attributed to the increase of thermal mobility of heavy Bi³⁺ and Ba²⁺ cations.     

Preparation, crystal structure and thermal decomposition study of some trimethylsilyl esters of dicarbamic acids

Some new trimethylsilylated dicarbamic acid esters 1–9 and 10 were prepared. Their thermal decomposition was studied in n-alkanes as media. The reactions were monitored by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS), respectively. Some N-silylated cyclic ureas 11–15 were also prepared from the corresponding esters 2–6 by thermolysis. The crystal structures of 2, 5 and 8 are also discussed. The crystal and molecular structures of 2 and 5 have very similar characteristics. Both molecules are sited via their molecular centre of symmetry on crystallographic inversion centres. The Carbamate groups are planar in all three cases as expected. An analysis of the data showed that the force due to Si---O conjugation which constrains the Si atom into the plane of the carbamate group is comparable to the crystal packing forces with a small out-of-plane movement being not unfavourable.     

Preparation,thermal decomposition,and crystal structure of Zn(II) 2-chlorobenzoate complex with nicotinamide

A new Zn(II) 2-chlorobenzoate complex, [Zn(2-ClC₆H₄COO)₂(nad)₂] (nad = nicotinamide), was synthesized and characterized by elemental analysis, infrared (IR) spectroscopy, mass spectrometry, thermal analysis, and X-ray structure determination. The mechanism of thermal decomposition of the complex was studied by TG/DTG, DTA, IR spectroscopy, and mass spectrometry. The thermal decomposition is characterized as a two-step process. Zinc oxide was found as the final product of the thermal decomposition performed up to 900°C. Mass spectrometry was used to determine the volatiles released during thermal decomposition. The IR spectrum indicates that carboxylate is coordinated to zinc in monodentate coordination. [Zn(2-ClC₆H₄COO)₂(nad)₂] crystallizes in the monoclinic system, space group Pn, a = 10.376(2) Å, b = 10.100(1) Å, c = 12.604(1) Å, β = 100.79(1)°. The zinc is tetrahedrally coordinated by two nitrogens of nicotinamide and two oxygens of 2-chlorobenzoate.     

Mixed ligand complexes of AEE hexafluoroacetylacetonates with diglyme: Synthesis,crystal structure and thermal behavior

The novel mixed ligand complexes [Ca(hfa)₂(diglyme)(H₂O)] (I), [Sr(hfa)₂(diglyme)(H₂O)] (II) and [Ba(hfa)₂(diglyme)₂] (III) (Hhfa = 1,1,1,5,5,5-hexafluoropentane-2,4-dione, diglyme = 2,5,8-trioxanonane) were synthesized by the reactions of the alkaline earth element (AEE) carbonates in n-hexane with a mixture of Hhfa and diglyme, and they were characterized by elemental analysis, ¹H and ¹³C NMR, and FTIR spectroscopy. The crystal structures of I–III, consisting of mononuclear isolated molecules, have been determined. The thermal behavior and composition of the vapor phase have been studied for I–III by thermal analysis at low pressure and mass spectrometry using a Knudsen cell. The stability of the mixed ligand complexes [M(hfa)₂(diglyme)_n] to the removal of diglyme molecules under heating decreases in the row I > II ≈ III, and only I evaporates as the mixed ligand complex after water removal.     

Yttrium-succinates coordination polymers: Hydrothermal synthesis, crystal structure and thermal decomposition

New polymeric yttrium-succinates, Y₂(C₄H₄O₄)₃(H₂O)₄·6H₂O and Y₂(C₄H₄O₄)₃(H₂O)₂, have been synthesized, and their structures (solved by single crystal XRD) are compared with that of Y₂(C₄H₄O₄)₃(H₂O)₂·H₂O. Three compounds were obtained as single phases, and their thermal behaviour is described.     

Structures and thermal properties of strontium and barium 1,3-propanediaminetetraacetates

In neutral and acidic solution, homonuclear s-block metal complexes [Sr₂(1,3-pdta)(H₂O)_3.5] _n (1), {[Ba₂(1,3-pdta)(H₂O)₆]·H₂O} _n (2), {[Sr(1,3-H₂pdta)]·(H₂O)} _n (3), and [Ba(1,3-H₂pdta)(H₂O)₃] _n (4) {1,3-H₄pdta=1,3-propanediamine-N,N,N′,N′-tetraacetic acid, CH₂[CH₂N(CH₂CO₂H)₂]₂} were isolated. In 1 and 2, hexadentate 1,3-pdta joins two metal ions via the diamine chain. In 3 and 4, the nitrogens of 1,3-H₂pdta were protonated and show no coordination. There is no coordinated water in 3, unusual coordination for strontium. In 4, the coordination number is nine and there are three coordinated waters for each barium. One carboxy group of pdta is free without coordination. Thermal decomposition shows that temperatures of ligand elimination start at 408, 423, 298, and 250?°C for 1–4, respectively. Acidic condition is favorable for preparation of metal oxide at low temperature.     

Synthesis, crystal structure and thermal behavior of a novel oxoborate SrBi2B4O10

A new compound, SrBi₂B₄O₁₀, has been grown by cooling a melt with the stoichiometric composition. It is triclinic, P−1, a=6.819(1), b=6.856(1), c=9.812(2) Å, α=96.09(1), β=109.11(1), γ=101.94(1)°, V=416.5(1) Å³, Z=2. The crystal structure of the compound has been solved by direct methods and refined to R₁=0.050 (wR₂=0.128). The structure contains Bi-O pseudolayers build up from Bi-O chains involving oxocentred OBi₃ triangles. Sr atoms and [B₄O₉]⁶⁻ isolated anions (4B:3Δ□:<2Δ□>Δ) are located between the Bi-O packages.The thermal treatment as well as DSC experiment showed that the compound melts above 800 °C presumably according to the peritectic reaction: SrBi₂B₄O₁₀ ↔ SrB₂O₄+SrB₄O₇+ Liquid. According to high-temperature X-ray powder diffraction study thermal expansion of SrBi₂B₄O₁₀ structure is anisotropic (α₁₁=13, α₂₂=9, α₃₃=2, α_V=24×10⁻⁶ °C⁻¹).     

Synthesis, crystal structure and thermal behavior of Sr3B2SiO8 borosilicate

Single crystals of Sr₃B₂SiO₈ were obtained by solid-state reaction of stoichiometric mixture at 1200 °C. The crystal structure of the compound has been solved by direct methods and refined to R1=0.064 (wR=0.133). It is orthorhombic, Pnma, a=12.361(4), b=3.927(1), c=5.419(1) Å, V=263.05(11) Å³. The structure contains zigzag pseudo-chains running along the b axis and built up from corner sharing (Si,B)−O polyhedra. Boron and silicon are statistically distributed over one site with their coordination strongly disordered. Sr atoms are located between the chains providing three-dimensional linkage of the structure.The formation of Sr₃B₂SiO₈ has been studied using annealing series in air at 900-1200 °C. According powder XRD, the probe contains pure Sr₃B₂SiO₈ over 1100 °C. The compound is not stable below 900 °C. In the pseudobinary Sr₂B₂O₅-Sr₃B₂SiO₈ system a new series of solid solutions Sr_3−xB₂Si_1−xO_8−3x (x=0-0.9) have been crystallized from melt. The thermal behavior of Sr₃B₂SiO₈ was investigated using powder high-temperature X-ray diffraction (HTXRD) in the temperature range 20-900 °C. The anisotropic character of thermal expansion has been observed: α_a= −1.3, α_b=23.5, α_c=13.9, and α_V=36.1×10⁻⁶ °C⁻¹ (25 °C); α_a= −1.3, α_b=23.2, α_c=5.2, and α_V=27.1×10⁻⁶ °C⁻¹ (650 °C). Maximal thermal expansion of the structure along of the chain direction [0 1 0] is caused by the partial straightening of chain zigzag. Hinge mechanism of thermal expansion is discussed.     

Synthesis,crystal structure and magnetic properties of a new macrocyclic trinuclear CuII-CuII-CuII complex

A new oxamido-bridged trinuclear copper(II) complex [(CuL)₂Cu](ClO₄)₂·0.5H₂O (L?=?the dianion of 2,3-dioxo-5,6,14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclotetradeca-7,12-diene) has been synthesized by self-assembly and characterized. X-ray diffraction analysis reveals that the title complex is monoclinic, space group P2₁, with a?=?16.213(5), b?=?9.811(3), c?=?18.802(6)?Å, β?=?96.790(5)°. The central copper(II) ion lies in a distorted octahedral environment. Terminal coppers have square pyramidal coordination geometry. Magnetic measurements show there is strong antiferromagnetic interaction between the central and the terminal Cu(II) ions.     

Synthesis and characterization of ZnO nanoparticles by thermal decomposition of a curcumin zinc complex

ZnO nanoparticles were generated by thermal decomposition of a binuclear zinc (II) curcumin complex as single source precursor. Thermal behavior of the precursor showed a considerable weight loss at about 374 °C by an exothermic reaction with a maximum weight loss rate of 14%/min. Complete decomposition of precursor was observed within 49 min with a heating rate of 10 °C/min. Synthesized nanoparticles have been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and selected area electron diffraction microscopy. Results revealed monodispersed hexagonal zincite structure with an average size of 117 ± 4 nm.     

Synthesis,crystal structure and DNA interaction studies of three coordination polymers with mixed ligand

Three coordination polymers [Mn(Nip)(Pbim)] _n (1), [Co(Nip)(Pbim)] _n (2) and [Zn(Nip)(Pbim)] _n (3) [5-nitroisophthalate (Nip) and 2-(2-pyridyl)benzimidazole (Pbim)] were synthesised and characterised by elemental analysis, IR and single-crystal X-ray diffraction. Single-crystal X-ray diffraction analysis reveals that 1, 2 and 3 have 1-D ladder chain structures constructed from μ₃-bridge Nip ligands and metal atoms. All of these chain-like structures are finally packed into supramolecular networks through hydrogen bonds and π–π stacking interactions. Fluorescence spectral method has been used for the study on the interaction of film sperm DNA with complexes. The results show that the corresponding fluorescence spectrum appeared and the intensity was enhanced with the growth of the concentration of DNA. All of the results indicate that there exists strong interaction of the complexes with DNA.     

Crystal structure and thermal decomposition mechanism of the supramolecular complex of barium chloride with inositol

The single crystal of [Ba(H2O)2(C6H12O6)2Cl2] was obtained based on the phase equilibrium results. Its structure was determined by X-ray crystallographic analysis. The crystals are monoclinic and in space group C2/c with a=1.901 7(2) nm, b = 0.682 13(8) nm, c = 0.162 60(2) nm,β=96.593(2)°and V= 2.095 3(4) nm3, Z= 4, DC=1.917 g·cm-3. In its solid state, this supramolecular complex is a three-dimensional network with double layers connected by hydrogen bondings. The molecule structure of [Ba(H2O)2(C6H12O6)2Cl2] has a central barium ion that is coordinated to two water molecules, two chlorides, and four hydroxyls from the two inosi-tols. Losing the coordinating water is controlled by random nucleation and growth mechanism (n = 2/3) and 3-dimensional diffusion mechanism (n=2).     

Synthesis,characterization, crystal structure,catalytic activity in oxidative bromination,and thermal study of a new oxidovanadium Schiff base complex containing O,N-bidentate Schiff base ligand

A new oxidovanadium(IV) Schiff base complex, VOL₂ (1), HL = 2-{(E)-[2- (bromoethyl)imino]methyl}-6-methoxy phenol, containing ethyl bromide pendant group was synthesized by direct reaction of HL and VO(acac)₂ in the ratio of 2 : 1 in methanol at reflux. The Schiff base ligand and its vanadyl complex were characterized by FT-IR spectra and CHN analysis. Additionally, the Schiff base ligand has been characterized by ¹H NMR spectroscopy. The crystal structure of 1 was also determined by single-crystal X-ray analysis, showing the distorted square-pyramidal N₂O₃ coordination around vanadium(IV). The catalytic activity of 1 was studied in the oxidative bromination of 2-nitrophenol as a model substrate, and different reaction parameters were investigated. The oxidative bromination of some organic compounds in the presence of 1 in optimal conditions showed that it was an effective and selective catalyst in those optimal conditions. Thermogravimetric analysis of 1 showed that it decomposed in two stages. 1 was thermally decomposed in air at 660 °C, and the XRD pattern of the obtained solid showed the formation of the V₂O₅ nanoparticles with average size of 34 nm .     

Synthesis, characterization and kinetics of thermal decomposition of dimeric peroxycarbamates

Several dimeric peroxycarbamates (PCs) have been synthesized by using cycloaliphatic and aromatic diisocyanates with mono- and di-hydroperoxides. The reactions were carried out under suitable conditions either in the presence of T-12 (dibutyltin dilaurate) as catalyst or in the absence of this catalyst. The products were characterized by IR-spectra and molecular weight measurements from isocyanate and peroxygen analyses. Thermal decomposition kinetics of these PCs were studied in THF solution at 80, 90 and 100 °C; the reactions were found to be first-order and decomposition rate constants (k_d) were found. Activation energies and frequency factors for the decomposition were calculated. Activation energies were found to be in the range 67-121 kJ mol⁻¹ and frequency factors were of the order of 10¹¹-10¹⁵ s⁻¹ depending on the structure of the PC. The results for the PCs agree well with literature values.     

Synthesis,crystal structure and reactivity of a new pentacoordinated chiral dioxomolybdenum(VI) complex

The novel tridentate chiral ligand 2,6-bis{[(1R,2S,4R)-2-hydroxy-1,3,3-trimethyl-bicyclo[2.2.1]hept-2-yl]}pyridine (1) was readily prepared by reaction of 2,6-dilithiopyridine with (R)-(−)-fenchone. Reaction of 1 with [MoO₂(acac)₂] resulted in the formation of the new metal-oxo five-coordinated complex [MoO₂(ONO)] (2) [ONO = (1 – 2H)]. The reactivity of 2 has been studied and the derivatives [MoS₂(ONO)] (3) and [MoO(O₂)(ONO)] (4) were prepared. The compounds 1–4 have been characterised by ¹H and ¹³C{¹H} NMR, microanalysis and IR spectroscopy. Furthermore, the molecular structures of 1 and 2 have been determined by single-crystal X-ray diffraction. The behaviour of 2 as catalyst in oxotransfer and in nucleophilic substitution of propargylic alcohols reactions has been tested.