Heat capacity and thermodynamic functions of MnBr2 · 4H2O and MnCl2 · 4H2O

The heat capacities of MnBr₂ · 4H₂O and MnCl₂ · 4H₂O have been experimentally determined from 10 to 300 K. The smoothed heat capacity and the thermodynamic functions (H°_TH°₀) andS°_T are reported for the two compounds over the temperature range 10 to 300 K. The error in these data is thought to be less than 1%. A subtle heat capacity anomaly was observed in MnCl₂ · 4H₂O over the temperature range 52 to 90 K. The entropy associated with the anomaly is of the order 0.4 J/mole K.     

A study of the reaction Na2SO4·10H2O→Na2SO4+10H2O in the temperature range 0 to 25°C

Thermogravimetry was used to obtain data on the isothermal rate of dehydration and hydration of the reaction Na₂SO₄·10H₂O→Na₂SO₄+10H₂O in the temperature range 10 to 25°C. The thermodynamic functions, ΔH, ΔG and ΔS were calculated and compared with data in the literature. The dissociation pressures of Na₂SO₄·10H₂O at temperatures in the range 0 to 25°C were measured in a volumetric dissociation apparatus. The results obtained were compared with those using thermogravimetry and the accuracy of the two techniques was assessed.     

NMR study of water reorientation in molybdic acids: MoO3 · 2H2O and yellow MoO3 · H2O

Proton NMR relaxation times (T₂, T₁, T_1?) are reported for powder samples of MoO₃ · 2H₂O and yellow MoO₃ · H₂O in the temperature range 150–325 K and at 20 and 60 MHz. No translation of hydrogen atoms is detected but the spin-lattice relaxation behavior indicates reorientation of H₂O molecules. The waters coordinated to Mo atoms undergo 180° flips (about their C₂ axes) with similar motional parameters in both compounds. The interlayer waters in MoO₃ · 2H₂O undergo 180° flips with different parameters. An assumed Arrhenius-type temperature dependence of correlation times leads to preexponential factors which are “anomalously” low. The possible involvement of temperature-dependent activation barriers is discussed.     

Conductivity and thermogravimetric studies of HTi2NbO7 · 2H2O and CsTi2NbO7

A detailed study was performed of the interrelationships of the lattice parameters, ionic conductivity, and infrared spectrum of HTi₂NbO₇ · 2H₂O as a function of dehydration. We have shown that the oxide layers in this ion-exchange compound are interespaced with water layers 2-molecules thick, providing a rare example of a bilayer hydrate. Bulk proton transport occurs through these layers, with a conductivity of (8 ± 4) × 10^?6 ohm^?1cm^?1 at 20°C. Upon heating to 55°C, 0.5 H₂O per formula was gradually lost, but the conductivity was essentially retained. Upon further heating to 62°C another 0.5 H₂O was rapidly lost, resulting in a conductivity drop of a factor of 10. Further water was gradually lost until HTi₂NbO₇ was reached at 220°C. The X-ray evidence revealed no discrete, fixed-composition hydrate phases, indicating a single isostructural phase from HTi₂NbO₇ · 2H₂O to HTi₂NbO₇, with a single continuously variable interlayer spacing. The bulk conductivity of CsTi₂NbO₇ was less than 10^?8 ohm^?1cm^?1.     

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.     

Strukturchemie titanorganischer verbindungen: Molekül- und kristallstruktur von [{(π-C5H5)2Ti(H2O)}2O](ClO4)2 · 2 H2O

(π-C₅H₅)₂TiCl₂ and cobaltous perchlorate react in aqueous solution to give [{(π-C₅H₅)₂Ti(H₂O)}₂O](ClO₄)₂ · 2 H₂O (I). Compound I crystallizes in the orthorhombic space group Fdd2 with Z 8 and lattice parameters a 28.893(5), b 17.433(4), c 10.312(3) Å. Results of an X-ray analysis of I (R 0.061): the (crystallographic) symmetry of the complex cation is C₂-2; Ti exhibits pseudotetrahedral coordination with a water molecule as one of the ligands; Ti—μ-O distance 1.83 Å; Ti—μ-O—Ti angle 176°; the geometry of the (π-C₅H₅)₂Ti unit in I corresponds closely to that in (π-C₅H₅)₂TiCl₂.     

Experimental Determination of the Isotherm at 15°C of the System Mg2+/Cl?, SO42–H2O

 The diagram of the ternary system Mg²⁺/Cl⁻, SO₄ ²⁻–H₂O was established at 15°C by means of analytical and conductimetric measurements. Three compounds were found in this diagram, which are MgSO₄·6H₂O, MgSO₄·7H₂O, and MgCl₂·6H₂O. The solubility field of MgSO₄·7H₂O is important whereas those of MgSO₄·6H₂O and MgCl₂·6H₂O are small. The compositions (mass-%) of the two invariant points determined by the two methods are: MgSO₄:MgCl₂=2.73:33.80 and MgSO₄: MgCl₂=3.38:28.91. Both the measured and the calculated isotherm at 15°C have been used for modelling of the diagram Mg²⁺/Cl⁻, SO₄ ²⁻–H₂O between 0 and 35°C. The polythermal invariant point was approximately located between 15 and 10°C.     

Ab initio molecular orbital calculations on H3AlOH2, (H2AlOH)2, and some related species

Ab initio molecular orbital calculations have been carried out on H₃AlOH₂, (H₂AlOH)₂, and some related species, and the charge distribution and bonding are discussed on the basis of population analyses. It is found that the equilibrium conformation around the O atom in H₃AlOH and (H₂AlOH)₂ is intermediate between trigonal and tetrahedral. The energy minima are, however, very shallow. In H₃AlOH₂ the angle between the Al-O bond and the H₂O plane is 27°, in (H₂AlOH)₂ the angle between the two O-H bonds and the Al₂O₂ ring plane is 25°. The energy of a planar conformation of H₃AlOH₂ is 0.19 kcal mol^-1, the energy of a planar conformation of (H₂AlOH)₂ 0.35 kcal mol^-1 above the equilibrium conformation. There is no indication for the formation of dative pπ-dπ bonds between O and Al in the two molecules. It is suggested that the conformation adopted by analogous alkyl derivatives, R₃AlOR'₂ and (R₂AlOR')_n is determined by intramolecular van der Waals repulsion.     

Enthalpy of formation of aqueous tungstate ion and of crystalline tungstic acid (H2WO4)

Calorimetric measurements of the enthalpy of reaction of WO₃(c) with excess OH^?(aq) have been made at 85°C. Similar measurements have been made with MoO₃(c) at both 85 and 25°C, to permit estimation of ΔH°=?13.4 kcal mol^?1 for the reaction WO₃(c)+2OH^?(aq)=WO^2?₄(aq)+H₂O(liq) at 25°C. Combination of this ΔH° with ΔH°_f for WO₃(c) leads to ΔH°_f=?256.5 kcal mol^?1 for WO^2?₄(aq). We also obtain ΔH°_f=?269.5 kcal mol^?1 for H₂WO₄(c). Both of these values are discussed in relation to several earlier investigations.     

一个新的夹心型杂多钨酸盐Na6(C5N2H7){[Na(H2O)2]3Co(H2O)5-[Co(H2O)]3(AsW9O33)2}•27H2O的晶体结构及性质

在pH＝7.5的水溶液中, Na₂WO₄•2H₂O, NaAsO₂, CoCl₂•6H₂O与对氨基吡啶反应, 得到了一种新的夹心型杂多钨酸盐Na₆(C₅H₇N₂){[Na(H₂O)₂]₃Co(H₂O)₅[Co(H₂O)]₃(AsW₉O₃₃)₂}•27H₂O单晶, 用X射线单晶衍射法及元素分析确定了其结构, 晶体属三斜晶系, P 空间群, 其晶胞参数为: a＝1.3276(8) nm, b＝1.7581(10) nm, c＝2.4381(14) nm, α＝70.954(9)°, β＝86.663(9)°, γ＝72.885(9)°, V＝5.136(5) nm³, Z＝2, R₁＝0.0608, wR₂＝0.0848 [I＞2σ(I)]. 在{[Na(H₂O)₂]₃Co(H₂O)₅[Co(H₂O)]₃(AsW₉O₃₃)₂}^7－阴离子中, 一个Co^2＋与聚阴离子{[Na(H₂O)₂]₃[Co(H₂O)]₃(AsW₉O₃₃)₂}^9－的一个端基氧共价连接, Co^2＋呈现出5和6两种配位数, 质子化的氨基吡啶正离子作为抗衡离子存在于晶体之中. 对标题化合物进行了IR, UV-Vis, TG-DSC表征. 对该化合物、Na₂WO₄•2H₂O及CoCl₂•6H₂O催化H₂O₂氧化乙醛的活性进行了比较研究, 该化合物的催化活性远优于简单化合物Na₂WO₄•2H₂O和CoCl₂•6H₂O.     

Phase equilibria in the system Na,K,Mg,Ca∥SO4,Cl-H2O at 25°C in the crystallization regions of MgCl2·6H2O, CaCl2·6H2O, and 2MgCl2·CaCl2·12H2O

The translation method is used to study equilibria in the system Na, K, Mg, Ca∥SO₄, Cl-H₂O at 25°C in the crystallization regions of MgCl₂·6H₂O, CaCl₂·6H₂O, and 2MgCl₂·CaCl₂·12H₂O. The participation of these salts in the formation of the geometrical images of the title system is determined. The relevant fragments of the equilibrium phase diagram are designed. Original Russian Text ? L. Soliev, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 5, pp. 841–845.     

A Novel Dimeric Polyoxotungstate Decorated by 3d-4f atoms: K4LaH[As2W20CuO67 (H2O)3]Cl2· 22.5H2O

A novel dimeric polyoxotungstate K₄LaH[As₂W₂₀CuO₆₇(H₂O)₃ ]Cl₂·22.5H₂O has been synthesized and characterized by IR, element analysis TG and cyclic voltammogram. The anion K₄LaH[As₂W₂₀CuO₆₇(H₂O) ₃]Cl₂·22.5H₂O can be characterized as two {As^IIIW₉O₃₃}⁹⁻ moieties linked via a {Cu(OH)}, a {W(H₂O)} and a {WO(H₂O)} group which total coordination numbers are respectively 5, 5, 6. An additional lanthanide atom connects the dimeric cluster via a W-O-La bond. The X-ray single crystal diffraction shows that it is in the triclinic system, space group P-1, with a = 12.287(6) ?, b = 20.197(1) ?,c=21.483(1)?,α = 62.584(8)°,β = 74.659(8)°,γ = 75.273(9)°,V = 4509(4)?³, Z = 2. To our known, the polyoxotungstate is the novel sandwich-type polyoxoanion, which is decorated by transition-metal and lanthanide atoms at the same time.     

Thermal behaviour of two new salts of malonic acid: Cu(C3H2O4)·4H2O and Cu(NH4)2(C3H2O4)2

Two new salts of malonic acid have been prepared: the copper(II) malonate tetrahydrate and the copper(II)-ammonium double malonate. Their study by thermal analysis (TG and DTA) leads to the following results:Cu(C₃H₂O₄)·4H₂O: the dehydration is rather complex and it is only under careful conditions that an intermediate hydrate Cu(C₃H₂O₄)·3H₂O could be traced. At about 170°C the dehydration is not ended (the salt holds yet about 0.15H₂O) and the anhydrous salt occurs only at about 240°C. It decomposes immediately leading to residues the composition of which depends upon the surrounding atmosphere; the part played by the gas given off is discussed.Cu(NH₄)₂(C₃H₂O₄)₂: this salt melts and decomposes simultaneously at about 190°C. During the decomposition the copper nitride Cu₃N forms as intermediate compound (as well as copper metal). Concerning the final residues of the decomposition the results and the conclusions are the same as the ones of the previous case.     

Thermal decomposition of N2H6GeF6 · H2O,isolation and characterization of intermediates

The thermal behaviour of N₂H₆GeF₆ · H₂O was investigated by TG, DTG and DTA measurements. The decomposition proceeded in three steps, in which anhydrous N₂H₆GeF₆ and N₂H₅GeF₅; were isolated and characterized by chemical analysis and vibrational spectroscopy. The X-ray powder photographs of the intermediates were indexed, namely, for N₂H₆GeF₆ on the basis of a monoclinic cell with a = 8.86(9), b = 9.29(2), c =7.40(0) Å, β = 85° and for N₂H₅GeF₅ on the basis of an ortrhorhombic cell with a = 8.43(5),b = 9.19(9), c = 7.43(6) Å.     

含二维水网的三维超分子[Ni(phen)2(H2O)2][Ni(PDC)2]•7H2O

在水溶液中合成了离子型配合物[Ni(phen)₂(H₂O)₂][Ni(PDC)₂]•7H₂O (H₂PDC＝吡啶-2,6-二甲酸, phen＝1,10-菲啰啉). 通过元素分析、红外光谱、单晶X射线衍射以及热重分析对配合物进行了表征. 晶体数据解析表明, 化合物属于三斜晶系, 空间群为P1, a＝1.0092(4) nm, b＝1.4599(6) nm, c＝1.4933(5) nm, α＝73.982(2)°, β＝78.652(2)°, γ＝75.184(3)°, V＝2.0256(13) nm³, Z＝2, F(000)＝1004, μ＝1.014 mm^－1, R₁＝0.0538, wR₂＝0.1493. 配合物中的结晶水分子形成一个(H₂O)₁₂水簇, (H₂O)₁₂水簇通过氢键连接为二维水网, 最终构成三维超分子网络.     

Eu(C10H9N2O4)(C10H8N2O4)(H2O)3]•0.5bipy•3H2O配合物的合成、晶体结构及荧光性质

在水-乙醇混合体系中, 以2-羰基丙酸水杨酰腙(C₁₀H₁₀N₂O₄)、2,2-联吡啶(C₁₀H₈N₂, 简写bipy)与Eu(NO₃)₃•4H₂O反应, 首次培养出黄色单晶[Eu(C₁₀H₉N₂O₄)(C₁₀H₈N₂O₄)(H₂O)₃]•0.5bipy•3H₂O. 该晶体属三斜晶系, 空间群为P-1, 晶胞参数a＝0.93392(16) nm, b＝1.3100(2) nm, c＝1.3895(2) nm, α＝97.205(3)°, β＝105.411(2)°, γ＝106.364(2)°, V＝15.35(2) nm³, Z＝2, μ＝2.118 mm^－1, D_c＝1.686 Mg/m³, F(000)＝786, R＝0.0116, wR＝0.0507, GOF＝0.995. 晶体测试结果表明, 该单晶结构为铕的9配位配合物, 两个2-羰基丙酸水杨酰腙分别以负一价和负二价酮式和三个水分子同时参与配位; 每个2-羰基丙酸水杨酰腙中的羧基氧、酰胺基中的羰基氧和C＝N中的氮与Eu^3＋配位, 形成两个共边的稳定五元环, 另三个配位原子则分别来自三个水分子中的氧原子, 该配合物在空间呈扭曲的单帽四方反棱柱, 而在不对称单位中还有游离的一个2,2-联吡啶分子和三个水分子, 这些游离分子与配位分子之间存在大量分子内和分子间氢键, 整个分子在空间呈三维网状结构. 发光性能测试表明该配合物具有很好的荧光性质.     

Synthesis, structural characterization and properties of a 3D infinitely extended structural rare earth coordination compound of K3{[Sm(H2O)7]2Na[α-SiW11O39Sm(H2O)4]2} · 14 H2O· 14 H2O

A 3D infinitely extended structural rare earth coordination compound with a formula of K₃{[Sm(H₂O)₇]₂Na[α-SiW₁₁O₃₉Sm(H₂O)₄]₂}·14H₂O has been synthesized by reaction of Sm₂O₃, HClO₄, NaOH with α-K₈SiW₁₁O39·nH₂O, and characterized by IR, UV spectra, ICP, TG-DTA, cyclic voltammetry, variable-temperature magnetic susceptibility and X-ray single-crystal diffraction. X-ray single-crystal diffraction indicates that the title compound crystallizes in a triclinic lattice, Pī space group, with a = 1.2462(3) nm, b = 1.2652(3) nm, c = 1.8420(4) nm, α = 87.45(3)°, β = 79.91(3)°, γ= 82.57(3)°, Z = 1, R₁ = 0.0778, wR₂ = 0.1610. Structural analysis reveals that Sm³⁺(1) coordination cation has incorporated into the vacant site of [α-SiW11O₃₉]⁸⁻ entity, forming the [α- SiW₁₁O₃₉Sm(H₂O)₄]⁵⁻ subunit. The two adjacent [α-SiW₁₁O₃9Sm(H₂O)4]⁵⁻ subunits are combined with each other through two Sm(1)-O-W bridges accompanying the formation of dimmer structural unit [α-SiW₁₁O₃₉Sm(H₂O)₄]₂ ¹⁰⁻ of the title compound. The neighboring dimmer structural units [α-SiW₁₁O₃₉Sm(H₂O)₄]₂ ¹⁰⁻ are linked to form the 1D chainlike structure by means of two Sm³⁺(2) and a Na⁺(1) coordination cations. The K⁺(1) cations connect the 1D packing chains constructing the 2D netlike structure, and adjacent netlike layers are also grafted by K⁺(2) cations to build the novel 3D infinitely extended structure. The result of TG-DTA curves manifests that the decomposition temperature of the title polyanionic framework is 554°C. The cyclic voltammetry measurements show that the title polyanion has the two-step redox processes in aqueous solution with pH = 3.1. Variable temperature magnetic susceptibility indicates the title compound obeys the Cruie-Weiss Law in the higher temperature range from 110 to 300 K, while in the lower temperature range from 2 to 110 K the comparatively strong antiferromagnetism interactions can be observed.     

Idle spin behavior of the shifted hexagonal tungsten bronze type compounds FeIIFeIII2F8(H2O)2 and MnFe2F8(H2O)2

Fe^IIFe^III₂F₈(H₂O)₂ and MnFe₂F₈(H₂O)₂, grown by hydrothermal synthesis ($\text{P ? 200}\text{MPa}\text{, T = 450}\text{or}\text{380°}\text{C}$), crystallize in the monoclinic system with cell dimensions (Å): a = 7.609(5), b = 7.514(6), c = 7.453(4), β = 118.21(3)°; and a = 7.589(6), b = 7.503(8), c = 7.449(5), β = 118.06(3)°, and space group $\text{C2}\text{m}\text{, Z = 2}$. The structure is related to that of $\text{WO}{}_3\text{·}\text{1}\text{3}\text{H}{}_2\text{O}$. It is described in terms of perovskite type layers of Fe³⁺ octahedra separated by Fe²⁺ or Mn²⁺ octahedra, or in terms of shifted hexagonal bronze type layers. Both compounds present a weak ferromagnetism below T_N (157 and 156 K, respectively). Mössbauer spectroscopy points to an “idle spin” behavior for Fe^IIFe^III₂F₈(H₂O)₂: only Fe³⁺ spins order at T_N, while the Fe²⁺ spins remain paramagnetic between 157 and 35 K. Below 35 K, the hyperfine magnetic field at the Fe²⁺ nuclei is very weak: H_hf = 47 kOe at T = 4.2 K. For MnFe₂F₈(H₂O)₂, Mn²⁺ spin disorder is expected at 4.2 K. This “idle spin” behavior is due to magnetic frustration.     

Crystal structure of a new coordination polymer [LaAg(Pydc)(HPydc)(C2O4)0.5(H2O)2]n (H2Pydc = pyridine-3,5-dicarboxylic acid)

A new 3D coordination polymer, [LaAg(Pydc)(HPydc)(C₂O₄)_0.5(H₂O)₂] _n (I) (H₂Pydc = pyridine-3,5-dicarboxylic acid), has been hydrothermally synthesized and characterized by elemental analyses and single crystal X-ray diffraction. The X-ray diffraction analysis reveals that I (C₁₅H₁₁AgLaN₂O₁₂) crystallizes in triclinic space group P $ \bar 1 $ \bar 1 and features an interesting 3D framework constructed by 2D layers via strong Ag-Ag interactions. Unit cell parameters for I (n = 1): a = 7.749(2), b = 8.316(1), c = 14.239(3) ?, α = 97.64(2)°, β = 100.12(2)°, γ = 94.37(2)°, and Z = 2.     

Influence of H3PMo12O40/SiO2 thermal treatment on adsorbed forms of formaldehyde and formic acid

Effect of the H₃PMo₁₂O₄₀/SiO₂(P-Mo-HPA) thermal treatment on adsorbed forms of HCOOH and H₂CO has been studied by IR spectroscopy. On the sample pretreated at 150°C, HCOOH adsorbed mainly as hydrogen-bonded complexes. The HPA calcination at 350°C resulted in the formation of surface formates along with hydrogen-bonded complexes. This proves the formation of coordinatively unsaturated surface cations (Lewis acid sites) during HPA dehydration. Alteration of the surface composition due to dehydration was found to have a major influence on the H₂CO adsorbed forms.