Analysis of thermoelastic properties and equation of state for cyclopentane,tetramethylsilane and 2,3-dimethylbutane

The thermoelastic properties and equation of state for liquids such as cyclopentane, tetramethylsilane and 2,3-dimethylbutane at high pressures and high temperatures have been analysed. The pressure dependences of thermal expansivity and isothermal compressibility have been determined for these liquids under pressure up to 100?MPa along different isotherms at selected temperatures in the range 208.0–298.15?K. We have formulated the pseudospinodal model for different liquids, along different isotherms for evaluating both thermal expansivity and isothermal compressibility with the change in pressure. It is found that the spinodal pressure is a characteristic property of the liquid depending only on temperature. The results obtained in this study are in good agreement with the experimental data reported in the literature. The plots between thermal expansivity versus pressure along different isotherms intersect each other for tetramethylsilane and 2,3-dimethylbutane. However, in the case of cyclopentane the plots do not intersect each other.     

Density and isothermal compressibility for two trialkylimidazolium-based ionic liquids at temperatures from (278 to 398) K and up to 120 MPa

In this paper, a densimeter based on vibrating tube principle is used to determine experimentally the density of 1-butyl-2,3-dimethylimidazolium tris(pentafluoroethyl)trifluorophosphate and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide at temperatures between (278.15 and 398.15) K and at pressures up to 120 MPa. The apparatus was calibrated by using water, vacuum and bromobenzene. The Tammann–Tait equation of state was used to correlate (p, T, ρ) results with standard deviations around 2 · 10⁻⁴ g · cm⁻³. Other volumetric properties, such as isothermal compressibility and isobaric thermal expansivity, were obtained from this equation. For each ionic liquid, the α_p isotherms present a crossing point within the experimental pressure range. Besides, the effect that the C2-methylation in the imidazolium cation provokes on density values is analyzed. The prediction ability of the group contribution methods of Gardas and Coutinho and Jacquemin et al. were tested with the experimental densities.     

Crystal Structure of Ternary Molybdate Rb5FeHf(MoO4)6 — a New Phase in the Rb2MoO4-Fe2(MoO4)3-Hf(MoO4)2 System

Physicochemical analysis (XRPA, DTA) was used to study phase equilibria in a ternary salt system Rb₂MoO₄-Fe₂(MoO₄)₃-Hf(MoO₄)₂ in the subsolidus region. Ternary molybdates with compositions 5:1:3, 5:1:2, and 1:1:1 have been found and synthesized. Crystal and thermal characteristics have been determined. Single crystals of the ternary molybdate Rb₅FeHf(MoO₄)₆ with a composition of 5:1:2 were grown. The crystal structure of the compound was solved using X-ray diffractometry (CAD-4 automatic diffractometer, MoK _α radiation, 1766 F(hkl), R = 0.0298). Hexagonal crystals with unit cell dimensions: a = b = 10.124(1) Å, c =15.135(3) Å, V = 1343.4(4) ų, Z = 2, ρ_calc = 4.008 g/cm³, space group P6₃. The mixed three-dimensional framework of the structure is formed from two sorts of MoO₄ tetrahedra and Fe and Hf octahedra linked through their common O-vertices. Rubidium atoms of three varieties occupy the large voids of the framework.Original Russian Text Copyright © 2004 by B. G. Bazarov, R. F. Klevtsova, A. D. Tsyrendorzhieva, L. A. Glinaskaya, and Zh. G. Bazarova__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 1038–1043, November–December, 2004.     

Densities,excess molar volume,isothermal compressibility,and isobaric expansivity of (dimethyl carbonate + n-hexane) systems at temperatures (293.15 to 313.15) K and pressures from 0.1 MPa up to 40 MPa

The densities of dimethyl carbonate, n-hexane and their mixtures were measured for 12 compositions at five different temperatures varying from (293.15 to 313.15) K and over the pressure range of (0.1 to 40) MPa. The densities of pure substances and their mixtures at atmospheric pressure were measured by a vibrating-tube densimeter. The densities at high pressures were measured by a variable-volume autoclave and precise analytical balance. The excess molar volume, isothermal compressibility, and isobaric expansivity were derived from the experimental densities.     

Liquid density of 1-pentanol at pressures up to 140 MPa and from 293.15 to 403.15 K

This work reports new density data (180 points) of 1-pentanol at twelve temperatures between 293.15 and 403.15 K, and pressures up to 140 MPa (every 10 MPa). A new Anton Paar vibrating-tube densimeter, calibrated with an uncertainty of ±0.5 kg m⁻³ was used to perform these measurements. The experimental density data were fitted with the Tait-like equation with low standard deviations. In addition, the isobaric thermal expansivity and the isothermal compressibility have been derived from the Tait-like equation.     

Structure of Ba Na Ethylenediaminetetraacetatocobaltate(III) Perchlorate, Na[Ba6(H2O)25][Co(Edta)]4(ClO4)9 · 5H2O

Crystals with uncommon composition NaBa₆[Co(Edta)]₄(ClO₄)₉ · 30H₂O (Edta⁴⁻ is ethylenediaminetetraacetic acid anion) were obtained with the following unit cell parameters: a = 14.8513(9) Å, b = 26.2361(15) Å, c = 15.1789(9) Å, α = 91.661(7)°, β = 113.035(7)°, γ = 89.897(7)°, space group P1¯. Each complex anion [Co(Edta)]⁻ is bonded through the carboxyl O atoms to five Ba atoms to give three-dimensional framework in a crystal. One perchlorate ion forms Ba-O-Cl-O-Ba bridge between the Ba atoms; four ClO ₄ ⁻ ions are isolated, while the remaining four ions act as monodentate ligands at the Ba atoms. The water molecules (25 in sum) complete the coordination sphere of the Ba atoms to eight-, nine-, or ten-vertex polyhedron. Four water molecules are in the closest surrounding of the Na atom, one H₂O molecule is isolated.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 8, 2005, pp. 590–595.Original Russian Text Copyright © 2005 by Zabel, Poznyak, Pawlowski.     

Studies on (SCN)2M(NCS)2Hg2(p-tolyl)2 and (SCN)2M(NCS)2Hg2(α-naphthyl)2 and their complexes

p-Tolyl mercury thiocyanate and α-naphthyl mercury thiocyanate react with Co(NCS)₂2py and form a bimetallic pink compound of formula (py)₂(SCN)₂Co(NCS)₂Hg₂R₂ (R = p-tolyl and α-naphthyl group). On heating this compound in vacuum a blue compound (SCN)₂Co(NCS)₂Hg₂R₂ is formed. Nickel analogues (SCN)₂Ni(NCS)₂Hg₂R₂ are formed by direct reaction of p-tolyl or α-naphthyl mercury thiocyanate with nickel thiocyanate. (SCN)₂Co(NCS)₂Hg₂R₂ and (SCN)₂Ni(NCS)₂Hg₂R₂ act as Lewis acids and form complexes with bases. The Lewis acids and their complexes with various bases have been characterized by elemental analyses, molar conductance, molecular weight, magnetic moment, infrared and electronic spectral studies. These studies reveal that both the Lewis acids are monomers. In (SCN)₂Co(NCS)₂Hg₂R₂ the CO(II) has tetrahedral geometry, where as in (SCN)₂Ni(NCS)₂Hg₂R₂ the Ni(II) has octahedral geometry through elongated axial bondings with SCN-groups of other molecules. Thiocyanate bridging of the type R-Hg-SCN-M [M = Co(II), Ni(II)] is present in the compounds. Pyridine and dimethylsulphoxide form adducts with these compounds by coordinating at Co(II) or Ni(II). The thiocyanate bridge is retained in these complexes. 2-2′bipyridyl ruptures the thiocyanate bridging in both the Lewis acids and forms cationic-anionic complexes of the type [M(L-L)₃][RHg(SCN)₂]₂. In both the type of complexes Co(II) and Ni(II) possess octahedral environment. The “softness” values have been used in a novel manner in proposing the structure of the complexes.     

Densities and derived thermodynamic properties of binary (alkanol + boldine) mixtures in the compressed liquid region

In this work, densities of two binary systems of {alkanol (ethanol and 1-propanol) + boldine} are measured at temperatures from (313 to 363) K and pressures up to 20 MPa using an Anton Paar vibrating tube densimeter. Each (alkanol + boldine) system was prepared at five diluted compositions with respect to the alkaloid. These are (x₂ = 0.0012, 0.0074, 0.0136, 0.0196, 0.0267) and (x₂ = 0.0018, 0.0046, 0.0077, 0.0112, 0.0142) mixed in ethanol and 1-propanol, respectively. Experimental densities are correlated using an empirical 6-parameter equation with deviations within 0.04%. Extrapolated densities at atmospheric pressure agree with the literature data. Isobaric expansivity, isothermal compressibility, thermal pressure coefficient, and internal pressure have been calculated.     

High-pressure density measurements for choline chloride: Urea deep eutectic solvent and its aqueous mixtures at T = (298.15 to 323.15) K and up to 50 MPa

New measurements are reported for the densities of choline chloride: urea (REL) deep eutectic solvent and its aqueous mixtures over the temperature range (298.15 to 323.15) K and pressures up to 50 MPa. The experimental data were used to derive other properties such as isothermal compressibility, isobaric expansivity and excess molar volume. A Tait-type equation was used to correlate accurately the high-pressure density data to temperature, T, pressure, P, and composition, x. The excess molar volumes of {REL (1) + H₂O (2)} mixtures were also investigated and represented as a function of all three variables, T, P, x, using an empirical equation. Results indicate that the correlations used in this work can be satisfactorily used to predict the densities of the studied systems at different conditions of temperature, pressure and composition.     

The metastable Ni7±xS6, and mixed Ni6±x(S1−ySey)5, phases

The closely related, narrowly non-stoichiometric, metastable as well as thermodynamically stable “phases” in the metal-rich part of the Ni–S phase diagram near the nominal composition Ni_7±xS₆ have been carefully re-investigated via electron diffraction and transmission electron microscope imaging. Two quite distinct polymorphs have been identified, a minority incommensurate interface-modulated polymorph and a (heavily twinned) majority I1a1, a=2a_p, b=2b_p, c=−a_p+c_p superstructure (of an underlying Bmmb, a_p3.3, b_p16.4, c_p11.3 Å parent structure) polymorph. The incommensurate polymorph is shown to be very closely related to the only known polymorph of Ni_6±xSe₅ and is rapidly stabilized to room temperature upon doping of the sulfide compounds with selenium.     

Diamine incorporated compounds derived from polymeric nickel(II) fumarates and oxalates: Crystal structure, spectral and thermal properties of [Ni(en)3](O2CCHCHCO2)·3H2O and [Ni(en)3](O2CCO2)

Lewis-base mediated fragmentation of polymeric nickel(II) fumarate and oxalate are attempted using chelating σ-donor diamines like ethylenediamine (en) and 1,3-diaminopropane (dap) in various conditions which yielded [Ni(en)₃](fum)·3H₂O (1), [Ni(en)₃](ox) (2), [Ni(dap)₂(fum)] (3) and [Ni(dap)(ox)]·2H₂O (4). While 1 and 2 are molecular products each containing octahedral [Ni(en)₃]²⁺ moieties and the anionic dicarboxylate species, 3 and 4 are dap-incorporated polymeric products. The fumarate derivative 1 containing [Ni(en)₃]²⁺ moieties crystallizes in the monoclinic space group C2/c with a = 17.899(4) Å, b = 11.747(2) Å, c = 10.748(2) Å, β = 125.59(3)°, V = 1837.7(6) ų, Z = 4, while the oxalate analogue 2 is seen to be in the trigonal space group P−31c with a = 8.8770(13) Å, b = 8.8770(13) Å, c = 10.482(2) Å, γ = 120°, V = 715.3(2) ų, Z = 2. The octahedral [Ni(en)₃] units in both 1 and 2 are seen to be strongly H-bonded to the dicarboxylate moieties through the coordinated en units leading to a three-dimensional network. However, in 1 the water molecules also take part in the H-bonding and contribute to the overall 3D structure. In both 1 and 2 the crystal packing is done with the [Ni(en)₃]²⁺ units with absolute configuration Λ(δδδ) and its mirror conformer with Δ configuration in exactly equal numbers. Spectral (IR and UV–Visible) and magnetic measurements were carried out and some of the ligand-field parameters like D_q, B and β were evaluated for all the four compounds. These values suggest the presence of octahedrally coordinated nickel(II) in all the four complexes. Spectral data suggest that 3 has the two chelating dap moieties and the fumarate coordinated in η¹ form through both its carboxylate moieties while 4 has one chelating dap and the oxalate moiety coordinated in η⁴-bis-chelating form. Though both 1 and 2 are made of the same type of [Ni(en)₃]²⁺ units their thermograms give entirely different thermal features; 1 showing three clearly successive and step-wise dissociation of each en unit while 2 having a combined loss of two en units in the first thermal step. The relevant thermodynamic and kinetic parameters like E_a and ΔS also could be evaluated for various thermal steps for the compounds 1–4 using Coats–Redfern equation.     

The oxidation mechanisms of Cu54Ni45Mn1 (Constantan) tapes: Kinetic analysis

The kinetic parameters, namely the triplet activation energy E_A, model function f(α) or g(α) and pre-exponential factor A of the oxidation of Constantan tapes in 1 atm of oxygen have been determined from both isothermal and non-isothermal thermogravimetry. For isothermal experiments, with temperatures ranging from 650 °C to 900 °C, the results from direct conversion of the weight increase as a function of the time and curve fitting, are compared with the isoconversion method. For the non-isothermal experiments, with heating rates from 1 °C/min to 20 °C/min, comparison is made between the Friedman differential method and the integral methods of Kissinger, Ozawa and Li and Tang. All methods give apparent activation energies with relative standard deviations as low as 3%. The results converge to the identification of three stages in the oxidation behaviour. A parabolic law for reaction extents α below 15% with E_A = 246 ± 7 kJ mol⁻¹, ln A = 14.3, is followed by two linear stages with E_A = 244 ± 4 kJ mol⁻¹ and ln A = 15.3 for 0.18 < α < 0.35 and E_A = 228 ± 15 kJ mol⁻¹, ln A ≈ 13 for α > 45%, respectively.     

Thermophysical properties of (diphenyl ether + biphenyl) mixtures for their use as heat transfer fluids

Experimental measurements of density, viscosity and thermal conductivity are reported for pure diphenyl ether and three different binary mixtures of diphenyl ether and biphenyl including the eutectic point. Density has been measured for the liquid phase at temperatures ranging from (298.15 to 363.15) K and for pressures up to 45 MPa using a high-pressure vibrating tube densimeter. A Tammann–Tait correlation of the experimental densities has been proposed for each composition. From these correlations, isothermal compressibility, isobaric thermal expansivity and internal pressure have been determined. Moreover, viscosity and thermal conductivity were experimentally determined at atmospheric pressure for several temperatures by using a rolling ball viscometer and a device based in the hot-wire technique, respectively. All the experimental devices used to determine the thermophysical properties were checked finding good agreements with previous literature data. The experimental viscosity values were correlated using the Vogel–Fulcher–Tammann, Avramov–Milchev and MYEGA equation.     

Structure and Thermal Properties of [Rh(NH3)5Cl](WO4)x(MoO4)1s-x (x = 0, 0.5, 1)

The isostructurality of [Rh(NH₃)₅Cl](WO₄) _x (MoO₄)_1s-x (x = 0, 0.5, 1) complex salts is shown, and their thermal properties are compared. In a hydrogen atmosphere, transformations begin at T ∼ 200°C. According to the powder XRD data, the phase composition of the end products is markedly different. For the Rh—Mo system, the dependence (V/Z) of the atomic volume on the composition is presented. The thermal decomposition product [Rh(NH₃)₅Cl](MoO₄) (T _fin = 800°C) is shown to be the disordered Mo_0.5Rh_0.5 solid solution (a = 2.757(2) ?, c = 4.428(4) ?, P6₃/mmc space group).     

Di- and tetranulcear Ru complexes of phenylene-1,4-diaminotetra(phosphonite), p-C6H4[N{P(OC6H4OMe-o)2}2]2 and their catalytic investigation towards transfer hydrogenation reactions

The stoichiometric reaction of phenylene-1,4-diaminotetra(phosphonite), p-C₆H₄[N{P(OC₆H₄OMe-o)₂}₂]₂ (P₂NФNP₂) (1) with [RuCl₂(p-cymene)]₂ in acetonitrile produces cis,cis-[{RuCl₂(CH₃CN)₂}₂(P₂NФNP₂)] (2), whereas the similar reaction of 1 with [RuCl₂(p-cymene)]₂ in THF medium affords a tri-chloro-bridged tetrametallic complex, [{(η⁶-p-cymene)Ru₂(μ₂-Cl)₃Cl}₂(P₂NФNP₂)] (3) irrespective of the stoichiometry and reaction conditions. The formation and structure of complexes 2 and 3 are assigned through various spectroscopic and micro analysis data. The molecular structure of 2 is confirmed by single crystal X-ray diffraction study. The catalytic activities of complexes 2 and 3 have been investigated in transfer hydrogenation reactions.     

Reactions of tungsten and molybdenum propargyl complexes with Co2(CO)8, Co4(CO)12, and Cp2Mo2(CO)4. A crossover study of formation of (CO)3 Cp(CO)2

The nature of the protonation reaction of (

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o(CO)₃ (M = Mo, W; R = Me, Ph, p-MeC₆H₄) (2) (obtained from (CO)₃CpMCH₂CCR (1) and Co₂(CO)₈) to give (CO)₃ Cp(CO)₂ (3) was further investigated by a crossover experiment. Thus, reaction of an equimolar mixture of 2b (M = W, Cp = η⁵-C₅H₅, R = Ph) and 2e (M = W, Cp = η⁵-C₅H₄Me; R = p-MeC₆H₄) with CF₃COOH affords only 3b (same M, Cp, and R as 2b) and 3e (same M, Cp, and R as 2e) to show an intramolecular nature of this transformation. Reaction of (CO)₃CpWCH₂CCPh (1b) with Co₄(CO)₁₂ was also examined and found to yield 2b exclusively. Treatment of 1 with Cp₂Mo₂(CO)₄ at 0–5°C provides thermally sensitive compounds, possibly (CO)₂Cp

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oCp(CO)₂ (5), which decompose at room temperature to give Cp₂Mo₂(CO)₆ as the only isolated product.     

Syntheses and Structure Determination of Nine-Coordinate (NH4)3[TbIII(nta)2(H2O)]·4H2O and Eight-Coordinate (NH4)3[ErIII(nta)2] Complexes

Syntheses and structure determination of Tb^III and Er^III complexes with nitrilotriacetic acids (nta) are reported. Their crystal and molecular structures, molecular formulas, and compositions were determined by single-crystal X-ray structure analyses and elementary analyses, respectively. The crystal of the (NH₄)₃[Tb^III(nta)₂(H₂O)]·4H₂O complex belongs to the monoclinic crystal system and C2/c space group. Crystal data are as follows: a = 16.357(8) Å, b = 8.552(4) Å, c = 17.390(9) Å, β = 104.748(7)°, V = 2352.6(19) ų, Z = 4, Mr = 675.32, D_c = 1.932 g·cm⁻³, μ = 3.112 mm⁻¹, and F(000) = 1368. The final R and Rw are 0.0220 and 0.0494 for 2357 (I > 2σ(I)) unique reflections, R and Rw are 0.0266 and 0.0510 for all 5613 reflections, respectively. The Tb^IIIN₂O₇ moiety in the [Tb^III(nta)₂(H₂O)]³⁻ complex anion has a pseudo-monocapped square antiprismatic nine-coordinate structure, in which the eight coordinate atoms (two N and six O) are from two nta ligands and the water molecule is coordinated to the central Tb^III ion directly as the ninth coordinate atom. The crystal of the (NH₄)₃[Er^III(nta)₂] complex belongs to the trigonal crystal system and R-3^c space group. Crystal data are as follows: a = 7.9181(16) Å, b = 7.9181(16) Å, c = 54.27(2) Å, γ = 120°, V = 2946.7(14) ų, Z = 6, Mr = 597.61, D _c = 2.021 g·cm⁻³, μ = 4.345 mm⁻¹, and F(000) = 1770. The final R and Rw are 0.0295 and 0.0673 for 677 (I > 2σ(I)) unique reflections, R and Rw are 0.0366 and 0.0700 for all 4827 reflections, respectively. The Er^IIIN₂O₆ part in the [Er^III(nta)₂]³⁻ complex anion is an eight-coordinate structure with a pseudo-dicapped octahedron, in which the eight coordinate atoms (two N and six O) are from two nta ligands.Original Russian Text Copyright © 2004 by J. Wang, X. D. Zhang, Y. Wang, Y. Zhang, Z. R. Liu, J. Tong, and P. L. Kang__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 1067–1075, November–December, 2004.     

Structure, crystal chemistry and thermal evolution of the δ-Bi2O3-related phase Bi9ReO17

The thermal evolution and structural properties of fluorite-related δ-Bi₂O₃-type Bi₉ReO₁₇ were studied with variable temperature neutron powder diffraction, synchrotron X-ray powder diffraction and electron diffraction. The thermodynamically stable room-temperature crystal structure is monoclinic P2₁/c, a=9.89917(5), b=19.70356(10), c=11.61597(6) Å, β=125.302(2)° (R_p=3.51%, wR_p=3.60%) and features clusters of ReO₄ tetrahedra embedded in a distorted Bi–O fluorite-like network. This phase is stable up to 725 °C whereupon it transforms to a disordered δ-Bi₂O₃-like phase, which was modeled with δ-Bi₂O₃ in cubic Fm3¯m with a=5.7809(1) Å (R_p=2.49%, wR_p=2.44%) at 750 °C. Quenching from above 725 °C leads to a different phase, the structure of which has not been solved but appears on the basis of spectroscopic evidence to contain both ReO₄ tetrahedra and ReO₆ octahedra.     

Synthesis, characterization and crystal structure of Me2NC6Ch---CHC5H4N(C2H5)[La(TTA)4](TTA --- α-thenoyltrifluoroacetonato)

The complex (E)-N-ethyl-4-(2-(4′-dimethylaminophenyl)ethnyl)pyridinium tetrakis(α-thenoyltrifluoracetanoto)lantanum(III) was synthesized, and its crystal structure was determined by single-crystal X-ray crystallography and refined to the final R of 0.046 and R_w of 0.052. IR, electronic absorption spectroscopy (UV-vis) and thermogravimetric and differential thermal analysis (TG-DTA) for the complex are also resported.     

Synthesis and Structure of the Supramolecular Adduct Formed by the [Mo3S4(H2O)7Cl22+ Cluster Complex with Cucurbituril: {[Mo3S4(H2O)7Cl2](C36H36N24O12)} Cl2·10H2O

Slow crystallization of an HCl solution containing cucurbituril (C₃₆H₃₆N₂₄O₁₂) and a triangular molybdenum cluster aqua complex [Mo₃S₄(aq)]⁴⁺ yielded a supramolecular adduct of { [Mo₃S₄(H₂O)₇Cl₂]×(C₃₆H₃₆N₂₄O₁₂₎Cl₂·10H₂O composition. The molecular and crystal structure of the adduct were established by single crystal X-ray diffraction. Monoclinic crystal system, space group P2₁/c, a = 21.4762(2) Å, b = 14.6853(1) Å, c = 24.6480(3) Å; β = 112.8366(5)°, V _cell = 7164.26(12) ų, Z = 4, ρ_calc = 1.725 g/cm³.Original Russian Text Copyright © 2004 by E. V. Chubarova, D. G. Samsonenko, J. H. Platas, M. N. Sokolov, and V. P. Fedin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 950–954, September–October, 2004.