Characterization and thermal decomposition of Mg<Subscript>2</Subscript>KH(AsO<Subscript>4</Subscript>)<Subscript>2</Subscript>·15H<Subscript>2</Subscript>O

In this work, we present first data on the infrared and Raman spectroscopic characteristics, thermal analysis and solid-state transformations of Mg₂KH(AsO₄)₂·15H₂O, which is a unique example of an acid salt containing dimeric units [H(AsO₄)₂] in its crystal structure. The infrared and Raman spectra recorded at ambient conditions have been studied, and an assignment of the observed vibrational bands has been proposed considering the crystal structure data. The thermal behavior of Mg₂KH(AsO₄)₂·15H₂O has been investigated by simultaneous TG/DTA/mass spectrometry experiments in the temperature range up to 1000 °C at different heating rates, and new data on the thermal stability and thermal dehydration of Mg₂KH(AsO₄)₂·15H₂O have been obtained. The phase composition after the dehydration processes in the temperature interval of 300–650 °C has been studied by combination of powder XRD and IR spectroscopic analyses. The spectroscopic and thermal properties of Mg₂KH(AsO₄)₂·15H₂O have been compared to those of the isostructural phosphate salt Mg₂KH(PO₄)₂·15H₂O.     

Thermal studies on thorium(IV) complexes of 1-butyl-1-methylpiperazinium iodide

Thorium(IV) complexes of the type Th(NO₃)₄·3L·2C₂H₅OH, Th(SCN)₄·L·C₂H₅OH and Th(SO₄)₂·2L·2C₂H₅OH (L=1-butyl-1-methylpiperazinium iodide(I) have been synthesised. From thermogravimetric (TG) curves, the decomposition pattern of the compounds has been analysed. The order, activation energy and apparent activation entropy of the thermal decomposition reaction have been elucidated. The heat of reaction has been calculated from differential thermal analysis (DTA) studies.     

Thermal dehydration of inorganic salts in water-saturated nitrogen

The thermal dehydrations of CoSO₄ · 6H₂O, NiSO₄ · 6H₂O and MnSO₄ · H₂O have been investigated by TG, DTG, and DTA in water-saturated nitrogen. The starting temperatures and the “activation energy” values for each step are reported.     

Syntheses and characterization of new MnII and FeII complexes with 4′-(4-pyridyl)-2,2′ : 6′,2″-terpyridine (pyterpy), [Mn(pyterpy)(MeOH)2(OAc)](ClO4) and [Fe(pyterpy)2](SCN)2 · MeOH

Two new Mn^II and Fe^II complexes with 4′-(4-pyridyl)-2,2′ : 6′,2″-terpyridine (pyterpy), [Mn(pyterpy)(MeOH)₂(OAc)](ClO₄) (1) and [Fe(pyterpy)₂](SCN)₂ · MeOH (2) have been synthesized and characterized by CHN elemental analysis, IR spectroscopy, and structurally analyzed by single-crystal X-ray diffraction. The thermal stabilities of these compounds were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The potentially tetradentate pyterpy ligand is a tridentate donor to both Mn(II) and Fe(II). The non-coordinated pyridyl interacts via O–H ··· N and C–H ··· N hydrogen bonds with adjacent molecules in 1 and 2, respectively, to form inversion symmetric dimers. Compound 1 is further extended into infinite hydrogen bonded chains via pairs of O–H ··· O_acetate hydrogen bonds.     

Zum Hydratisierungs- und Dehydratisierungsverhalten von Magnesiumhydrogensulfat

On the Hydration and Dehydration Behaviour of Magnesium Hydrogensulfate Mg(HSO₄)₂ · H₂O has been prepared by crystallization from diluted sulfuric acid. The thermal destruction leads to the formation of siccative Mg(HSO₄)₂. This process is reversible, i. e., Mg(HSO₄)₂ rehydrates during cooling under formation of Mg(HSO₄)₂. H₂O. Due to further water reception Mg(HSO₄)₂ · H₂O decomposes at a temperature of 50°C forming Kieserite (MgSO₄ · H₂), MgSO₄ · 1,25H₂O, sulfuric acid, and water. During gentle warming of this heterogenous phase mixture it reacts under reconstruction of Mg(HSO₄)₂ · H₂O. The thermal measurements have been carried out in dynamic as well as in static gas atmosphere. The strong dependence of the decomposition temperatures from the partial pressure of the gaseous products could be demonstrated by in situ X-ray measurements.     

CoC2O4·2H2O在空气中的热分解动力学研究

纳米Co3O4具有尖晶石结构,Co3 占据八面体位,具有较高的晶体场稳定化能,在空气中低于800℃时十分稳定,是优良的催化材料[1]。Co3O4还可以作为高比能锂离子电池负极材料具有非常好的电化学活性,充放电容量高达960m A h·g-1。纳米Co3O4在紫外、可见及近红外区域都有良好的吸收效果,因此,在隐身技术、保温节能技术等领域具有潜在的应用前景。所以,Co3O4超细粉体的制备和应用研究具有十分重要的意义。我们合成了草酸盐先驱物制备纳米Co3O4用作隐身材料,因此对先驱物的热分解过程研究是十分必要的。热分析方法在了解先驱物热分解反应的物理…     

Mixed‐ligand Copper(II) Complexes with N‐isopropyl‐iminodiacetato(2‐) and C‐phenyl‐imidazole Ligands. Crystal Structures of H2iPIDA, [Cu(iPIDA)(H2ϕim)(H2O)]·3H2O and [Cu(iPIDA)(H5ϕim)]n

The crystal of the N‐isopropyl‐iminodiacetic acid ( 1 ) consists of a 3D H‐bonded framework where the zwitterion (H₂iPIDA^±) is intra‐stabilized by one N⁺‐H···O interaction and both carboxyl are half‐protonated and involved in linear O‐H···O inter‐molecular bridges of 2.46 Å. The mixed‐ligand complexes [Cu(iPIDA)(H2?im)(H₂O)]·3H₂O ( 2 ) and [Cu(iPIDA)(H5?im)]_n ( 3 ) have also been synthesized and studied by thermal, spectral, magnetic and X‐ray diffraction methods. Both complexes exhibit a square base pyramidal coordination, type 4+1. Compound 3 is the less steric hindered 'remote' isomer, with H5?im instead of H4?im.     

Some transition metal nitrate complexes with hexamethylenetetramine

Three hexamethylenetetramine (HMTA) metal nitrate complexes such as [M(H₂O)₄(H₂O-HMTA)₂](NO₃)·4H₂O (where M=Co, Ni and Zn) have been prepared and characterized by X-ray crystallography. Their thermal decomposition have been studied by using dynamic, isothermal thermogravimery (TG) and differential thermal analysis (DTA). Kinetics of thermal decomposition was undertaken by applying model-fitting as well as isoconversional methods. The possible pathways of thermolysis have also been proposed. Ignition delay measurements have been carried out to investigate the response of these complexes under condition of rapid heating.     

Thermal properties of oxide

To evaluate the thermal stability of oxide glasses, various criteria have been used. Not only the simple parameters, as characteristic temperatures and values of activation energy and enthalpy changes, but also the combined criteria E/RTp and kf(T) have been taken into account. Three glasses with the composition of Li₂O·2SiO₂ (a), Li₂O_·2SiO₂·0.03TiO₂ (b) and Li₂O·2SiO₂·0.1TiO₂ (c) were prepared and the validity of the criteria was tested by applying them to these glasses. The results indicate that the sequence thermal stability of the studied glass system vs. crystallization depends not only on their composition but also on the used criteria. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal properties of solid complexes with biologically important heterocyclic ligands

The thermal decomposition of the complexes Mg(SCN)₂(2-OHpy)₄·H₂O(I), Mg(SCN)₂(quin)₄·2H₂O(II) and Mg(SCN)(quinox)₄·5H₂O(III) (2-OHpy–2-hydroxypyridine, quin–quinoline, quinox–quinoxaline) has been investigated in static air atmosphere at 20–1000 °C by means of thermogravimetry (TG), differential thermal analysis (DTA), and infrared (IR) spectroscopy. The composition of the complexes had been identified by means of elemental analysis and complexometric titration. The possible scheme of destruction of the complexes is suggested. The final product of the thermal decomposition was MgS. IR data suggest that heterocyclic ligands were coordinated to Mg(II) through the nitrogen atom of their heterocyclic ring. Thiocyanate group is also coordinated through the nitrogen atom.     

Polyhalite and its analogous triple salts

Polyhalite (K₂SO₄ · MgSO₄ · 2CaSO₄ · 2H₂O) and analogue triple salts, where Mg²⁺ is substituted by Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺, have been synthesized. The salts were characterized by thermal analysis, Raman spectroscopy and X-ray powder diffraction. Diffraction patterns and Raman spectra resemble those of natural polyhalite, except K₂SO₄ · CuSO₄ · 2CaSO₄ · 2H₂O. The latter corresponds to the mineral leightonite, which is structurally different.     

Crystal structures of complexes of 3,5,6-tris(2-pyridyl)-1,2,4-triazine: [Pb(TPT)(NO3)2] n and [Pb(TPT)2(ClO4)(H2O)] · ClO4 · H2O

Two new Pb(II) complexes, [Pb(TPT)(NO₃)₂] _n (1) and [Pb(TPT)₂(ClO₄)(H₂O)] · ClO₄ · H₂O (2) (TPT is the abbreviation of 3,5,6-tris(2-pyridyl)-1,2,4-triazine), have been synthesized and characterized by single-crystal X-ray diffraction. Lead(II) in the compounds of 1 and 2 is nine coordinate (rare mode), PbN₃O₆ and PbN₆O₃, respectively. Both have hemidirected coordination geometries. The supramolecular features in these complexes are guided/controlled by hydrogen bonding and weak directional intermolecular C–H ··· O and π ··· π interactions. The thermal stabilities of 1 and 2 were investigated by thermogravimetric measurements.     

Tb(III) complexes with 1-phenyl-3-methyl-4-stearoyl-pyrazol-5-one as a material for luminescence Langmuir–Blodgett films

Abstract

Synthesis and properties of new luminescent amphiphilic Tb(III) complexes [TbL₃·2H₂O]·3H₂O, TbL₃·bipy, [H₃O][TbL₄]·6H₂O and [H₃O][TbL′₃L]·H₂O, where HL is 1-phenyl-3-methyl-4-stearoylpyrazolone-5 and HL′ is 1-phenyl-3-methyl-4-formylpyrazolone-5, are reported. The complexes have been characterized by elemental and thermal analysis, FTIR and luminescence spectroscopy methods. Formation and properties of Langmuir–Blodgett films of the complexes are described.     

粉状白钨酸的研究——ⅩⅫ.六聚钨酸二甲基亚砜加合物的制备

1968年,Fuchs等首次用控制水解法从WO(CH_3)_4中获得了六聚钨酸盐,它的阴离子W_6O_(19)~(2-)结构也已被测定。迄今六钨酸盐主要还是局限于几个多碳有机胺盐。以粉状白钨酸为原料,在二甲基亚砜(DMSO)中制得了一系列DMSO配位的多价金属的六钨酸盐晶体,并测定了其中部分盐类的晶体结构。但六聚钨酸仍未     

Study on the non-isothermal kinetics of decomposition of 4Na<Subscript>2</Subscript>SO<Subscript>4</Subscript>·2H<Subscript>2</Subscript>O<Subscript>2</Subscript>·NaCl

The non-isothermal decomposition kinetics of 4Na₂SO₄·2H₂O₂·NaCl have been investigated by simultaneous TG-DSC in nitrogen atmosphere and in air. The decomposition processes undergo a single step reaction. The multivariate nonlinear regression technique is used to distinguish kinetic model of 4Na₂SO₄·2H₂O₂·NaCl. Results indicate that the reaction type Cn can well describe the decomposition process, the decomposition mechanism is n-dimensional autocatalysis. The kinetic parameters, n, A and E are obtained via multivariate nonlinear regression. The n ^th-order with autocatalysis model is used to simulate the thermal decomposition of 4Na₂SO₄·2H₂O₂·NaCl under isothermal conditions at various temperatures. The flow rate of gas has little effect on the decomposition of 4Na₂SO₄·2H₂O₂·NaCl.     

Preparation of non-valence compounds of zinc(II) with 1,2- and 1,4-benzenedicarboxylic acids via self-assembly

Nanostructured non-valence compounds based on coordination compounds of zinc(II) with phthalic and terephthalic acids have been prepared. The purity and composition of prepared compounds have been elucidated from X-ray diffraction analysis, IR spectroscopy, elemental analysis, and thermogravimetry studies; thermal decomposition of the non-valence compounds has been studied as well. The prepared self-assembled compounds are co-precipitated with one water molecule and 1.5 acetic acid molecules per unit of the dicarboxylic acid: [Zn₄(OH)₆·o-C₆H₄(COO)₂]·H₂O·1.5CH₃COOH and [Zn₄(OH)₆·p-C₆H₄(COO)₂]·H₂O· 1.5CH₃COOH.     

Solubility in ternary aqueous systems including calcium chlorate and diethanolamine (triethanolamine) at 25°C

Solubility in ternary aqueous systems including calcium chlorate and diethanolamine (triethanolamine) has been studied at 25°C. Solubility diagrams have been constructed. Solubility curves consist of three branches corresponding to the crystallization of calcium chlorate, diethanolamine (triethanolamine), and compound Ca(ClO₃)₂ · NH(C₂H₄OH)₂ or Ca(ClO₃)₂ · N(C₂H₄OH)₃. The compounds have been isolated and identified by chemical analysis, X-ray powder diffraction, and thermal analysis.     

Syntheses,structures, and luminescence of two Zn(II) coordination polymers based on 5-(4-imidazol-1-yl-phenyl)-2H-tetrazole and carboxylates

Reactions of Zn(II) salts, 5-(4-(1H-imidazol-1-yl)phenyl)-1H-tetrazolate (HIPT) and 2-mercaptobenzoic acid or 2-propyl-1H-imidazole-4,5-dicarboxylic acid (H₃PrIDC), result in two mixed-ligand coordination polymers (CPs), [Zn₂(IPT)(DSDB)(OH)]_n (H₂DSDB = 2,2′-disulfanediyldibenzoic acid, 1) and [Zn₂(IPT)(PrIDC)(H₂O)]_n (H₃PrIDC = 2-propyl-1H-imidazole-4,5-dicarboxylic acid, 2). Compound 1 possesses a 2-D structure built by 1-D [Zn(IPT)]_n chains and DSDB^2? connectors, in which the DSDB^2? is generated via in situ reaction from 2-mercaptobenzoic acid. It displays a new intricate 4-nodal {3·4·6·7·8·9}{3·6·7·8·9·10}{3·8·9}{4·6·8} topology. Compound 2 displays a 3-D framework with new 3-connected topology with Schläfli symbol of (4·8·10) (8·12²), in which the 1-D Zn-carboxylate chains were bridged by 3-connected IPT^? ligands. The thermal stabilities and luminescence properties of 1 and 2 have also been studied. The compounds exhibit intense solid-state fluorescent emissions at room temperature.     

Mössbauer spectrometica analysis of thermal decomposition products of phosphate and oxalate coatings on steel

The deterioration of zinc, zinc—calcium and manganese phosphate coatings and oxalate coatings on steel on heating was investigated by conversion electron Mössbauer spectrometry. and the chemical change of the coatings was analysed on the basis of the thermal characteristics of Zn₃(PO₄)₂·4H₂O, Zn₂Fe(PO₄)₄·4H₂O, CaZn₂(PO₄)₂·2H₂O, Fe₃(PO₄)₂·8H₂O. (Mn, Fe)₅H₂(PO₄)₄·4H₂O and FeC₂O₄·2H₂O. The steel substrate beneath the coatings influenced the thermal decomposition and evaporation of coating materials under the various heating atmospheres. The heat resistance of these coatings and the state of the substrate were also investigated.     

Synthesis,thermal investigations and kinetic data of Zn(BF<Subscript>4</Subscript>)<Subscript>2</Subscript>·6H<Subscript>2</Subscript>O

The thermal dehydration and decomposition of Zn(BF₄)₂·6H₂O have been studied by TG, DTA and DSC analyses. It is found that the dehydration occurs in two steps. Following the experimental results a thermal decomposition scheme of the compound under investigation is proposed. The enthalpies of dehydration have been determined as well as the formal kinetic parameters are presented.