On the thermal decomposition of K2PdCl4 in a hydrogen atmosphere

The decomposition of single crystals and powders of K₂PdCl₄ in a hydrogen atmosphere was investigated by means of thermogravimetry (TG) at temperatures between 85 and 170°C, and by optical microscopy. The rate of decomposition is controlled by a combined process of nucleation and growth. The activation energy was calculated to be 15.2 ± 0.5 kcal mol^?1 for single crystals and 13.5 ± 0.4 kcal mol^?1 for powders. The results are compared with those obtained for K₂PtCl₄.An attempt was made to explain the differences in the orientation relationships, previously determined by X-ray diffraction, between K₂PtCl₄ and K₂PdCl₄, Rb₂PdCl₄ and K₂PdBr₄ and their decomposition products with a different kinetic behaviour.     

The thermal decomposition of K2Pt(CN)4Br2 and K2Pt(CN)4

The thermal decomposition of K₂Pt(CN)₄Br₂ was studied by thermogravimetry, evolved gas analysis, X-ray diffraction and infrared spectroscopy. The reduction of the platinum occurs in several steps, each evolving cyanogen. The first step corresponded to the formation of a complex of apparently Pt(III) with bridging cyanide ions. The second and third steps which form Pt(II) with primarily terminal cyanide ions and finally the metal, are not well resolved. K₂Pt(CN)₄-8H₂O first lost water of hydration and then a single molecule of cyanogen corresponding to the formation of platinum metal and KCN.     

六氯合铂酸钾与金属硫蛋白的体外反应

本文报道了K₂PtCl₆与兔肝Zn₇MT-Ⅱ和apoMT-Ⅱ的反应包含一个氧化还原反应和一个取代反应。通过紫外可见光谱、园二向色谱、柱层析和X-光电子能谱研究了该反应的性质、铂在反应产物中的键合位置和氧化态。金属硫蛋白(MT)被氧化成单体、双聚和多聚产物，其中含有分子间和分子内CyS-SCy二硫键。Pt(Ⅳ)被还原成Pt(Ⅱ)然后键合于产物中。随着K₂PtCl₆与MT的反应摩尔比和反应时间的增加，键合于产物中的Pt(Ⅱ)的计量数增加而蛋白中所含Zn(Ⅱ)的量减少。当Zn₇MT与4和超过10摩尔的K₂PtCl₆反应时，分别得到了Pt₄Zn₄MT和Pt₈MT。当apoMT与7及超过25倍的K₂PtCl₆在pH 2条件下反应时，分别得到了Pt₇MT和Pt₁₅MT。动力学数据表明K₂PtCl₆与apoMT的反应比与Zn₇MT的反应快。     

Thermal decomposition of iron(VI) oxides, K2FeO4 and BaFeO4, in an inert atmosphere

The thermal decomposition of solid samples of iron(VI) oxides, K₂FeO₄·0.088 H₂O (1) and BaFeO₄·0.25H₂O (2) in inert atmosphere has been examined using simultaneous thermogravimetry and differential thermal analysis (TG/DTA), in combination with in situ analysis of the evolved gases by online coupled mass spectrometer (EGA-MS). The final decomposition products were characterized by ⁵⁷Fe Mössbauer spectroscopy. Water molecules were released first, followed by a distinct decomposition step with endothermic DTA peak of 1 and 2 at 273 and 248 °C, respectively, corresponding to the evolution of molecular oxygen as confirmed by EGA-MS. The released amounts of O₂ were determined as 0.42 and 0.52 mol pro formula of 1 and 2, respectively. The decomposition product of K₂FeO₄ at 250 °C was determined as Fe(III) species in the form of KFeO₂. Formation of an amorphous mixture of superoxide, peroxide, and oxide of potassium may be other products of the thermal conversion of iron(VI) oxide 1 to account for less than expected released oxygen. The thermogravimetric and Mössbauer data suggest that barium iron perovskite with the intermediate valence state of iron (between III and IV) was the product of thermal decomposition of iron(VI) oxide 2.     

Solid state decomposition studies on tetraperoxo species of transition metals. Kinetics of the isothermal decomposition of K3Nb(O2)4 and K3Ta(O2)4

The kinetics of the isothermal decomposition of K₃Nb(O₂)₄ and K₃Ta(O₂)₄ have been investigated using a constant volume apparatus in the temperature ranges 428–451 and 416–464 K, respectively. The α-time plots for both these solids are predominantly deceleratory in nature. They obey the unimolecular decay law ?log(1 ? α) = kt over a long period of time. Facile nucleation has been attributed to two factors, namely the fine size of the crystallites of the reactants and the strain imposed by four peroxide rings. The activation energies for K₃Nb(O₂)₄ and K₃Ta(O₂)₄ are 126.53 and 95.86 kJ mole^?1 respectively.     

Interaction of methanol with hydrogen sulfide in the presence of K2WO4/Al2O3

Kinetic data show that in the presence of K₂WO₄/Al₂O₃, methanethiol is largely produced by the reaction of H₂S with metanol and partly with dimethyl ether. Dimethyl sulfide is formed during the interaction of methanethiol with methanol, of H₂S with dimethyl ether and as a result of methanethiol disproportionation. Methane and carbon oxides are the decomposition products of methanethiol and dimethyl sulfide and of methanol and dimethyl ether, respectively.

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, K₂WO₄/Al₂O₃ H₂S — . , H₂S . , — .

     

A high hydroarylation activity of K2PtCl4/AgOTf catalyst in the reaction of propiolic acid with unactivated and activated arenes

A mixed catalyst K₂PtCl₄/AgOTf showed the highest activity for hydroarylation of propiolic acid, among palladium and platinum catalysts. This catalyst was effective for hydroarylation with less reactive benzene to give cis-cinnamic acid in good yield. The hydroarylation with toluene gave a higher yield of hydroarylation products than that with benzene and resulted in ortho/para orientation with an almost statistical ratio, suggesting that the result is very close to that of the Friedel-Crafts alkylation with methyl bromide or p-nitrobenzyl chloride. Hydroarylation of propiolic acid with other electron-rich arenes proceeded efficiently in the presence of the K₂PtCl₄/AgOTf catalyst in trifluoroacetic acid forming cis-cinnamic acids in good to high yields. This method was also applied to hydroarylation of ethyl propiolate.     

NMR studies of complex formation between H2PtCl4 and SnCl2 in organic solvents

Complex formation of H₂PtCl₄ with SnCl₂ in isopropanol and isopropanol-acetone solutions with the molar ratio [Sn]: [Pt]=1.0 has been studied by using¹⁹⁵Pt and¹¹⁹Sn NMR method.

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¹⁹⁵Pt ¹¹⁹Sn H₂PtCl₄ co SnCl₂ - Sn:Pt=1,0.

     

Deuterium isotope effects in the thermal dehydration of K2Mg(SO4)2 · 6H2O

Deuterium isotope effects in the thermal stability, enthalpy change, and kinetic parameters were examined by means of TG-DSC recorded simultaneously for the dehydration stages of

The thermal stability and enthalpy change for the hydrate were smaller than those for its deuterium analog in stage (1). In addition, the rate constant for the hydrate was larger than that for the deuterate in this stage. As for stages (2) and (3), any isotope effect in these parameters was not recognized in practice. The correlation of these isotope effects observed in stage (1) is briefly discussed     

Phase formation in the K2MoO4-Lu2(MoO4)-Hf(MoO4)2 system and the structural study of triple molybdate K5LuHf(MoO4)6

Interactions in the ternary system K₂MoO₄-Lu₂(MoO₄)₃-Hf(MoO₄)₂ have been studied by X-ray powder diffraction and differential thermal analysis. A new triple (potassium lutetium hafnium) molybdate with the 5: 1: 2 stoichiometry has been found. Single crystals of this molybdate have been grown. Its X-ray diffraction structure has been refined (an X8 APEX automated diffractometer, MoK _α radiation, 1960 F(hkl), R = 0.0166). The trigonal unit cell has the following parameters: a = 10.6536(1) ?, c = 37.8434(8) ?, V = 3719.75(9) ?, Z = 6, space group R c. The mixed 3D framework of the structure is built of Mo tetrahedra sharing corners with two independent (Lu,Hf)O₆ octahedra. Two sorts of potassium atoms occupy large framework voids. Original Russian Text ? E.Yu. Romanova, B.G. Bazarov, R.F. Klevtsova, L.A. Glinskaya, Yu.L. Tushinova, K.N. Fedorov, Zh.G. Bazarova, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 5, pp. 815–818.     

Solid state photodecomposition studies of K4Ti(O2)4·2H2O, K3Ta(O2)2F4 and K2V2O3(O2)2F2

The compounds K₄Ti(O₂)₄·2H₂O, K₃Ta(O₂)₂F₄ and K₂V₂O₃(O₂)₂F₂ undergo photolysis in the solid state. The photolysis kinetics obey the parabolic rate equation p = kt^1/2 and indicate a monoexcitation process for the photolysis. These features are similar to those reported previously for peroxo complexes. The mechanism of evolution of oxygen reported earlier appears to be the same in all these solids.     

Thermal decomposition of syngenite, K2Ca(SO4)2·H2O

The thermal decomposition of syngenite, K₂Ca(SO₄)₂·H₂O, formed during the treatment of liquid manure has been studied by thermal gravimetric analysis, differential scanning calorimetry, high temperature X-ray diffraction (XRD) and infrared emission spectroscopy (IES). Gypsum was found as a minor impurity resulting in a minor weight loss due to dehydration around 100 °C. The main endothermic dehydration and decomposition stage of syngenite to crystalline K₂Ca₂(SO₄)₃ and amorphous K₂SO₄ is observed around 200 °C. The reaction involves a solid-state re-crystallisation, while water and the K₂SO₄ diffuse out of the existing lattice. The additional weight loss steps around 250 and 350 °C are probably due to presence of larger syngenite particles, which exhibit slower decomposition due to the slower diffusion of water and K₂SO₄ out of the crystal lattice. A minor endothermic sulphate loss around 450 °C is not due to the decomposition of syngenite or its products or of the gypsum impurity. The origin of this sulphate is not clear.     

Interaction of K2PdCl4 with aminoalkyldiphosphonic acids

Complexing of K₂PdCl₄ with 3-amino-1-hydroxypropylidene-1,1-diphosphonic acid (AHPDP) and 1-aminoethylidene-1,1-diphosphonic acid (AEDP) was studied by pH titration, spectrophotometry, and ³¹P NMR spectroscopy using metal to ligand mole ratios of 1: 1 and 1: 2. In equimolar complexes, AHPDP is coordinated to palladium(II) via two phosphonic oxygen atoms, whereas AEDP is coordinated via the amino nitrogen atom and a phosphonic oxygen atom. In the bisligand palladium(II) complex with AEDP, both ligand molecules are coordinated in a bidentate mode by the amino nitrogen atom and a phosphonic oxygen atom.     

Metastable Equilibrium in Quaternary System Li2SO4 ＋ K2SO4＋Li2CO3 ＋ K2CO3 ＋ H2O at 288 K

IntroductionThe Zhabuye salt lake, Tibet in China, is famousfor the high concentrations of lithium, boron, andpotassium in the world. The main components areLi , K , Na , B4O72 -, CO32 -, Cl-, SO42 -, andH2O, including rare elements such as Rb and Cs .The…     

Structure cristalline de K2SO4(SbF3)2

The crystal structure of K₂SO₄(SbF₃)₂ was determined by X-ray diffraction on a single crystal (R = 0.035 for 2264 reflections). There are two families of antimony atoms showing two different environments: AX₅E octahedron (6 coordination) and AX₆E 3.3.1 monocapped octahedron (7 coordination). The SO^2?₄ unit weakly bonded to four antimony atoms is not very distorted. This arrangement permits the minimization of π-E interactions. Infrared and Raman spectra are discussed in terms of diffraction results.     

Infrared spectra of KNaSO4 and K3Na(SO4)2

The infrared spectra, transmittance and polarized reflectance, of KNaSO₄ and K₃Na(SO₄)₂ are reported. Group theoretical analysis was carried out and a vibrational assignment proposed on basis of C_3v and D_3d symmetries. Factor group and site effects are discussed.     

Electrical properties of K2FeCl5·H2O and K2AlF5

The electrical conductivity of nominally pure K₂FeCl₅·H₂O and anhydrous K₂AlF₅ has been studied from 300 to 690°K. K₂FeCl₅·H₂O exhibits mixed ionic and electronic conduction, whereas K₂AlF₅ is a pure ionic conductor. The mass and charge transport processes in K₂FeCl₅·H₂O seem to be governed by deviations from both molecularity and stoichiometry. At elevated temperatures both potassium and chloride ions are mobile in K₂FeCl₅·H₂O.     

Mechanism of alkyl iodide reduction to alkanes in aqueous solutions of Na2PtCl4?NaI?HClO4

Platinum(II) catalyzes the reduction of alkyl iodides to alkanes according to a mechanism involving oxidative addition of RI to Pt(II), reduction of the product complex RPt(IV) to RPt(II) by iodide ions and protolysis of the latter particle.

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(II) , RI Pt^II, - RPt^IV RPt^II .

     

K2CdSnS4的溶剂热合成与晶体结构

利用溶剂热法合成了层状硫代锡(Ⅲ)酸镉(Ⅱ)化合物K₂CdSnS₄。单晶X-射线衍射分析结果表明,化合物属单斜晶系,C2/c空间群,a=1.1021(5)nm,b=1.1030(5)nm,c=1.5151(10)nm,α=90°,β=100.416(12)°,γ=90°,V=1.8114(17)nm³,Z=8,D_c=3.209g·cm^-3,M_r=437.60,μ=6.853mm^-1,F(000)=1600,λ=0.071073nm,R=0.1042,wR=0.2008。该化合物由类金刚烷[Cd₂Sn₂S₁₀]^8-结构单元互相连接形成层状结构。紫外-可见漫反射光谱研究表明,化合物为半导体,带隙为2.2eV。