Thermochemical Properties of Palladium(II) Chelates Involving Dialkyldithiocarbamates

The standard molar enthalpies of formation of crystalline dialkyldithiocarbamates chelates, [Pd(S₂CNR₂)₂], with R=C₂H₅, n-C₃H₇, n-C₄H₉ and i-C₄H₉, were determined through reaction-solution calorimetry in acetone, at 298.15 K. From the standard molar enthalpies of formation of the gaseous chelates, the homolytic (172.4±3.8, 182.5±3.2,150.9±3.1 and 162.6±3.1 kJ mol⁻¹) and heterolytic (745.0±3.8, 803.7±3.3,834.3±3.1 and 735.2±3.0 kJ mol⁻¹) mean palladium-sulphur bond-dissociation enthalpies were calculated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Kinetic Analysis of the Decomposition of Chelates of Di-alkyldithiocarbamate of Cd(II)

The thermal decomposition kinetics of the solid complexes Cd(S₂ CNR₂ )₂ , where R =C₂ H₅ , n -C₃ H₇ , n -C₄ H₉ or iso -C₄ H₉ , was studied by using isothermal and non-isothermal thermogravimetry. The superimposed TG/DTG/DSC curves revealed that thermal decomposition reactions occur in the liquid phase. The kinetic model that best fitted the experimental isothermal TG data was the one-dimensional phase-boundary reaction-controlled process R₁ . The thermal analysis data suggested the thermal stability sequence Cd(S₂ CNBuⁿ ₂ )₂ >Cd(S₂ CNPrⁿ ₂ )₂ >Cd(S₂ CNBuⁱ ₂ )₂ >Cd(S₂ CNEt₂ )₂ , which accords with the sequence of stability of the apparent activation energies. This revised version was published online in July 2006 with corrections to the Cover Date.     

Formation and Thermal Decomposition of Indium Oxynitride Compounds

During the reactions of lithium oxide with indium nitride, lithium nitride with indium oxide, and lithium nitride with lithium indate LiInO2, the formation of a previously unknown crystalline phase, of composition Li4InNO2, was observed. The course of thermal decomposition of the new compound was determined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mg(OH)2热分解反应的非等温动力学研究

用非等温动力学方法对氢氧化镁的热分解动力学进行了研究. 分解反应机理符合晶核形成及生长机理A，且随着升温速率的升高，机理由A2转变为A1.5. 根据Kissinger非机理方程计算和数值回归方法验证所得的分解反应活化能结果相互印证，约为148 kJ•mol^-1. 进一步研究发现，水蒸气的存在对氢氧化镁热分解反应具有非常明显的影响，可能是其动力学机理随升温速率升高而改变的主要影响因素.     

Thermal Decomposition of Thallium(I) Bis-oxalatodiaquaindate(III) Monohydrate

Thallium(I) bis-oxalatodiaquaindate(III) monohydrate was obtained by precipitation of indium(III) withoxalic acid from slightly acidic solution in the presence of thallium(I). The complex was subjected to chemical analysis. The thermal decomposition behavior of the complex was studied using TG, DTA and DTG 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 physicochemical investigations the structural formula of the complex was proposed as Tl[In (C₂O₄)₂ (H₂O)₂]⋅H₂O. This revised version was published online in August 2006 with corrections to the Cover Date.     

The Affinity of Gallium(III) and Indium(III) for Nitrogen Donor Ligands

Abstract

Dedicated to Professor Arthur Martell on the occasion of his seventy fifth birthday.

The complexes of In(III) and Ga(III) with a variety of nitrogen donor ligands were studied in aqueous solution by glass electrode potentiometry at 25°C in 0.1 M NaNO₃. The ligands were 2-aminomethylpyri-dine (AMPY), ethylenediamine (EN), N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (THPED), and N,N-bis(2-hydroxyethyl)glycine (BICIN). A variety of mixed ligand complexes of the MLOH type were detected with many of the above ligands as L. The logK₁ values obtained were with Ga(III) 8.40 (AMPY), 7.94 (THPED) 12.72 (EN), and In(III) 7.6 (AMPY), 8.20 (THPED), and 7.06 (BICIN). These formation constants are discussed in relation to previous predictions that In(III) and Ga(III) would have a substantial chemistry with nitrogen donor ligands. Of particular interest is the Ga(III) system with EN, where a very stable Ga(EN)³⁺ complex is formed, but no higher complexes except for hydrolyzed species such as Ga(EN)OH²⁺ and Ga(EN)(OH)₂ ⁺.     

Kinetic Analysis of the Thermal Decomposition of Synthetic Malachite by CRTA

The kinetic behavior of the thermal decomposition of synthetic malachite was investigated by means of CRTA under different conditions of reduced pressure, flowing gases and quasi-isobaric atmospheres. The thermal decomposition was found to proceed at lower temperatures under the influence of the self-generated gases, CO₂ and H₂O. From a viewpoint of chemical equilibrium, the normal and opposite effects on the overall kinetics were observed for the self-generated CO₂ and H₂O, respectively. The complexity of the present reaction is also reflected by the variations of the apparent kinetic parameters which depend on the applied and self-generated atmospheric conditions. The practical usefulness of CRTA when applied to a complicated thermal decomposition is discussed as exemplified by the kinetic approaches to the present reaction. This revised version was published online in August 2006 with corrections to the Cover Date.     

非等温热重分析三聚氰胺热分解动力学

采用非等温热重法对三聚氰胺的热分解动力学进行了研究,选定拟合结果更好的迭代法计算反应活化能,采用积分法结合36种动力学函数来判断三聚氰胺热分解的机理函数.得到了三聚氰胺热分解的动力学参数,即反应的动力学函数为g(α)=(1-α)-3-1,平均活化能Ea为142.38×103J/mol,指前因子A的平均值为1.98×10...     

Thermal Studies on Some Ionic Chelates of Hafnium(IV)

Ionic chelate complexes of kojic acid(I) and hafnium(IV) of the type [(η⁵-C₅H₅)₂HfL]⁺[MCl₃]^– (II)[HL=kojic acid; M=Zn(II), Cd(II), Hg(II), Cu(II)] have been synthesised and characterised by spectral studies (IR, UV, ¹H NMR and ¹³CNMR). Thermogravimetric (TG) and differential thermal analytical (DTA) studies have been carried out for these complexes and from the TG curves, the order and apparent activation energy for the thermal decomposition reactions have been elucidated. The various thermal studies have been correlated with some structural aspects of the complexes concerned. From DTA curves, the heat of reaction has been calculated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Impedance of Indium(III) Hexacyanoferrate Films: Effect of the Supporting-Electrolyte Cation

Films of indium(III) hexacyanoferrate are studied in nitrate solutions of lithium, sodium, potassium, and ammonium using cyclic voltammetry and faradaic impedance. Effect of the supporting-electrolyte cation on parameters of the equivalent circuit corresponding to the impedance spectra is analyzed. The charge transport at the electrode/film interface is shown to be slow. The cation bonding in a film is discussed.     

非等温TG—DTG法确定2,2‘—联吡啶—对甲氧基苯甲酸铕（Ⅲ）热分解 …

采用TG DTG和DTA技术研究了2,2' 联吡啶 对甲氧基苯甲酸铕(Ⅲ)在静态空气中的非等温热分解过程及动力学 ,根据TG曲线确定了热分解过程中的中间产物及最终产物 ,运用微分法与积分法对非等温动力学数据进行分析 ,推断出第一步的动力学方程为dα/dt=Aexp( E/RT)2(1 α)1/2 。     

Non-isothermal Kinetic Study of the Heterogeneous Thermal Decomposition of a Mannich Compound

The authors present data concerning the evaluation of kinetic parameters of the decomposition of a Mannich compound by using the classical method of constant heating rate thermal analysis and the new one of controlled rate thermal analysis (CRTA). The data processed using the CRTA method allow to obtain more reliable kinetic parameters according to the proposed reaction mechanism. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal Decomposition Kinetics of Some Di‐ and Triorganotin(IV) Carboxylates Derived from para‐Nitrophenylethanoic Acid

Thermogravimetric (TG) investigations of organotin(IV) carboxylates with the general formula R_mSnL_4−m (where R=CH₃, C₂H₅, n‐C₄H₉, C₆H₅, cyclo‐C₆H₁₁, n‐C₈H₁₇, m=2, 3, and L=para‐nitrophenylethanoate anion) have been performed. Derivative thermogravimetry (DTG) and differential thermal analysis (DTA) techniques, Horowitz‐Metzger method and the fundamental thermodynamic relations are used to evaluate the thermokinetic parameters of each thermal degradation pattern. Results reveal that the thermal stability is functional to Sn C and Sn O bonds. In the case of R₂SnL₂, activation energy, reaction order and pre‐exponential factor associated with the bulk degradation processes increase as the alkane chain length increases. Hence, Oct₂SnL₂ is thermally more stable than Bu₂SnL₂, which in turn is more resistant to thermal dissociation than Et₂SnL₂. The same phenomenon is not observed for R₃SnL compounds because their degradation is highly irregular. Furthermore, R₂SnL₂ has larger values of kinetic parameters than those of corresponding triorganotin(IV) para‐nitrophenylethanotes. Thermodynamic parameters of these compounds also reinforce the above facts.     

Kinetic Study of Thermal Decomposition of the DMIT Complex of Cobalt

In this work, a cobalt complex with dmit (1,3-dithiol-2-thione-4,5-dithiolate) as ligand was prepared and its thermal stability was studied by thermogravimetric analysis and kinetics by means of the Zsakó method and a non-linear method. For both methods, numerical binomial and polynomial filters were used, where points in the central interval were utilized. This revised version was published online in August 2006 with corrections to the Cover Date.     

具有新结构类型的化合物CsIn[PO_3(OH)]_2的合成与结构(英文)

水热法合成了新结构类型化合物CsIn[PO3(OH)]2,并通过单晶X--射线衍射表征结构。标题化合物空间群为P121/c1(No.14),晶体学参数为:Mr=439.69,mP56,a=0.53286(6)nm,b=0.91653(7)nm,c=1.47839(14)nm,β=93.849(9)°,V=0.7204(1)nm3,Z=4,Dx=4.054g·cm-3,μ=8.713mm-1,F(000)=800,R1=0.0325,wR2=0.0874。在该化合物中,2个InO6八面体和4个PO4四面体形成交连的六元环柱,并沿a轴方向形成近六方密堆积并连接成Cs 离子占据的十二元环结构隧道,六元环和十二元环连接构筑了三维网络结构。与类似化学计量比化合物Na2In2[PO3(OH)]4·H2O比较,标题化合物中十二元环的形成明显取决于隧道阳离子的大小,其拓扑构造可看作扩展的6,3-网格连接,化合物RbIn[PO3(OH)]2与之同构。     

Thermal decomposition of potassium bis -oxalatodiaqua-indate(III) monohydrate

Indium (III) is precipitated with oxalic acid in the presence of potassium nitrate maintaining an overall concentration of 0·125 M in HNO₃. Chemical analysis of the complex salt obtained indicates the formula, K[In(C₂O₄)₂]·3H₂O. Thermal decomposition studies show that the compound decomposes first to the anhydrous potassium indium oxalate and then to the final mixture of the oxides through formation of potassium carbonate and indium (III) oxide as intermediates. Isothermal study, X-ray diffraction pattern and IR spectral data support the proposed thermal decomposition mechanism.     

Study of Thermal Decomposition Kinetics of Low-temperature Reaction of Ammonium Perchlorate by Isothermal TG

The kinetics of the thermal decomposition of ammonium perchlorate at temperatures between 215 and 260°C is studied, in this work, by measuring the sample mass loss as a function of time applying the isothermal thermogravimetric method. From the maximum decomposition rate – temperature dependence two different decomposition stages, corresponding to two different structural phases of ammonium perchlorate, are identified. For the first region (215–235°C), corresponding to the orthorhombic phase, the mean value of the activation energy of 146.3 kJ mol^–1, and the pre-exponential factor of 3.43⋅10¹⁴ min^–1 are obtained, whereas for the second region (240–260°C), corresponding to the cubic phase, the mean value of the activation energy of153.3 kJ mol^–1, and the pre-exponential factor of 4.11⋅10¹⁴ min^–1 are obtained. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and Structure of a Hydrogen-bonding Assembled Three-dimensional Supramolecular Indium(III) Compound Involving One-dimensional Helices

The title compound [In(H2ip)(pdc)(H2O)] (H3ip = 5-hydroxyisophthalic acid, H2pdc = pyridine-2,6-dicarboxylic acid) has been synthesized and characterized by single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group P21/c with a = 13.830(8), b = 6.488(4), c = 17.632(10) , β = 92.510(10)°, C15H10InNO10, Mr = 479.06, V = 1580.6(15) 3, Z = 4, Dc = 2.013 g/cm3, F(000) = 944, μ = 1.557 mm-1, the final R = 0.0413 and wR = 0.0793 for 2950 observed reflections with I > 2σ(I). The In(III) ion is seven-coordinated in a slightly distorted penta-bipyramidal geometry. The mixed ligands connect the In(III) ions into 21 helical chains along the [010] direction, and the hydrogen bonds assemble the chains into a three-dimensional supramolecular network.     

Thermal Decomposition of BaC2O4·0.5H2O Studied by Stepwise Isothermal Analysis and Non-Isothermal Thermogravimetry

Thermal decomposition of BaC2O4·0.5H2O in air was studied by a combination of stepwise isothermal analysis (SIA) and non-isothermal thermogravimetry. The results from both techniques show that the crystal water is released in one step and that anhydrous barium oxalate is decomposed in one step, while BaCO3 decomposes in three steps to BaO, forming two intermediate compounds with the formulas of BaCO3·(BaO)2 and (BaCO3)0.5·(BaO)2.5. Reaction mechanism analyses using the data from SIA measurements show that the controlling mechanism for all the five decomposition steps in isothermal conditions is a two-dimensional phase-boundary controlled process. Kinetic parameters are obtained for the five decomposition steps from the non-isothermal thermogravimetric data. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal stability of poly(styrene) containing phosphorus in the mainchain

For many applications poly(styrene) must be treated to reduce its flammability. This is usually done by incorporating a flame retardant additive, usually an organohalogen compound, into the formulation as the polymer is being processed. A potentially very efficient way of introducing flame retardance would be to incorporate a suitable structural unit directly into the polymer. This can be done by using 2,4,4,5,5-pentaphenyl-1,3,2-dioxaphospholane as an initiator for styrene polymerization. The strained carbon–carbon bond of the phospholane undergoes homolysis at moderate temperatures to generate a diradical which initiates polymerization. The resulting polymer contains an O–P–O unit in the mainchain. Thermogravimetry indicates that the thermal stability of the polymer is quite comparable to that of poly(styrene) generated by conventional methods.