Thermodynamic Properties in Gold Phenylacetylide in the Range 0-330 K

The temperature dependence of the heat capacity of gold phenylacetylide in the range 13-330 K was measured in an adiabatic vacuum calorimeter with an accuracy of 0.3%. These data were used for calculating the thermodynamic functions C _p0(T), H ⁰(T) - H ⁰(0), S ⁰(T) - S ⁰(0), and G ⁰(T) - H ⁰(0) for the range 0-330 K. The standard entropy of formation _f S ⁰ of gold phenylacetylide from the elements at T 298.15 K and p 101.325 kPa was calculated. The thermodynamic properties of gold phenylacetylide and related silver and copper compounds were compared.     

Thermodynamic Properties of Dibenzo-24-crown-8 in the Range from T → 0 to 500 K

The temperature dependence of the heat capacity of dibenzo-24-crown-8 in the range 6-500 K was measured by adiabatic vacuum and dynamic calorimetry with an accuracy of 0.2-0.5%. The physical transformations of the title compound occurring on its heating and cooling within the above temperature range were revealed and characterized. From the experimental data obtained for dibenzo-24-crown-8, its thermodynamic functions C _4p ⁰(T), H ⁰(T) - H ⁰(0), S ⁰(T) - S ⁰(0), and G ⁰(T) - H ⁰(0) were calculated for the range from T 0 to 500 K; the standard entropy of formation from the elements, _s S ⁰, at T 298.15 K was also calculated. The fractal dimensions D in the heat capacity function of the multifractal version of the Debye heat capacity theory, characterizing the heterodynamic characteristics of the title compound, were calculated.     

Thermodynamic Properties of N-(Trimethylsily)ethyleneimine N-(Triethylsily)ethyleneimine and (Dimethylphenylsilyl)ethyleneimine Complexes with Zinc Chloride in the Range 0-340 K

Tmperature dependence of heat capacity of N-(trimethylsilyl)ethyleneimine, N-(triethylsilyl)-ethyleneimine, N-(dimethylphenylsilyl)ethyleneimine with zinc chloride was studied in the 5-340 K rangein an adiabatic vacuum calorimeter with 0.2% error. From the data obtained tge complexes thermodynamicfunctions C0 _p(T), H ⁰(T)-H ⁰(0), S ⁰(T)-S ⁰(0) and G ⁰(T)-H ⁰(0) are obtained in the 0-340 K, as well as fractal dimensions D and characteristic temperatures max for the functions of gractal heat capacity of solid substances.     

Thermodynamic properties of crystalline polymeric C60 phases in the temperature region from O → 0 to 340 E

The temperature dependences of the heat capacity C _p° = f(T) were studied in an adiabatic vacuum calorimeter for the orthorhombic, tetragonal, and rhombohedral polymeric C₆₀ phases in the 7—340 K temperature interval with an error of 0.2%. Comparative analysis of C _p° of these phases formed by stacking of one-dimensional and two types of two-dimensional polyfullerenes C₆₀, was performed, and their fractal dimensionalities D were determined for temperatures below 50 K. The thermodynamic functions of the crystalline polymeric C₆₀ phases were calculated in the temperature region from O 0 to 340 K: C _p°(T), H°(T) — H°(0), S°(T) — S°(0), and G°(T) — H°(0). Assuming that S°(0) = 0, the standard entropies of formation _f S° of these phases from graphite at T = 298.15 K and standard pressure were calculated. In addition, the entropies of transformation of the initial face-centered cubic phase of fullerite C₆₀ in the crystalline polymeric C₆₀ phases and entropies of their interconversions under the same conditions were estimated. The thermodynamic characteristics of the polymeric C₆₀ phases were reviewed.     

Thermodynamics of copper,silver, gold,and mercury acetylenides

Thermodynamic characteristics of the copper, silver, gold, and mercury acetylenides obtained from the data of precise calorimetric measurements in the region from 5 to 340 K are considered. Tables of the thermodynamic functions C _p°(T), H°(T) — H°(0), S°(T), and G°(T) — H°(0) at 0—340 K, standard enthalpies of combustion H _c°, and thermodynamic characteristics of formation of the acetylenides from simple substances H _f°, S _f°, G _f°, and logK _f° at 298.15 K and standard pressure are presented. Temperature plots of the heat capacity of the acetylenides were analyzed in the framework of Tarasov's theory and the fractal version of Debye's theory of heat capacity. The values of heat capacity of several acetylenides yet unstudied were estimated.     

Thermodynamic properties of first- and third-generation carbosilane dendrimers with terminal phenyldioxolane groups

The heat capacities of first- and third-generation carbosilane dendrimers with terminal phenyldioxolane groups are studied as a function of temperature via vacuum and differential scanning calorimetry in the range of 6 to 520 K. Physical transformations that occur in the above temperature range are detected and their standard thermodynamic characteristics are determined and analyzed. Standard thermodynamic functions C_p^ο(T), [H°(T) ? H°(0)], [S°(T) ? S°(0)], and [G°(T) ? H°(0)] in the temperature range of T → 0 to 520 K for different physical states and the standard entropies of formation of the studied dendrimers at T = 298.15 K are calculated, based on the obtained experimental data.     

Heat Capacities and Thermodynamic Properties of Fenpropathrin (C22H23O3N)

The heat capacities of fenpropathrin in the temperature range from 80 to 400 K were measured with a precise automatic adiabatic calorimeter. The fenpropathrin sample was prepared with the purity of 0.9916 mole fraction. A solid—liquid fusion phase transition was observed in the experimental temperature range. The melting point, T_m, enthalpy and entropy of fusion, _fusH_m, _fusS_m, were determined to be 322.48±0.01 K, 18.57±0.29 kJ mol^–1 and 57.59±1.01 J mol^–1 K^–1, respectively. The thermodynamic functions of fenpropathrin, H_(T)—H_(298.15), S_(T)—S_(298.15) and G_(T)—G_(298.15), were reported with a temperature interval of 5 K. The TG analysis under the heating rate of 10 K min^–1 confirmed that the thermal decomposition of the sample starts at ca. 450 K and terminates at ca. 575 K. The maximum decomposition rate was obtained at 558 K. The purity of the sample was determined by a fractional melting method.This revised version was published online in November 2005 with corrections to the Cover Date.     

Thermodynamic Properties of Styrenetricarbonylchromium, α-Methylstyrenetricarbonylchromium,and p-Methylstyrenetricarbonylchromium in the Range 0-450 K

The thermodynamic properties of styrenetricarbonylchromium, -methylstyrenetricarbonylchromium, and p-methylstyrenetricarbonylchromium were studied with adiabatic vacuum and dynamic calorimeters. The heat capacity in the range 5-450 K (error about 0.3% in most cases) and the temperatures and enthalpies of the phase transitions were determined. The experimental data were used to calculate the thermodynamic functions C ⁰ _p(T), H ⁰(T) - H ⁰(0), S ⁰(T), and G ⁰(T) - H ⁰(0) for the range from 0 to 330-400 K, and also the isochoric heat capacity C _v and its lattice (_Cv,latt) and atomic (C _v,at) contributions for the range from 0 K to T ⁰ _m; the parameters = C ⁰ _p/C _v were evaluated. The thermodynamic properties were considered in relation to the composition and structure of the compounds.     

Thermodynamics of the reaction between poly-1,1,2-trichlorobuta-1,3-diene and poly(ethylene imine) to form interpolymer

Thermodynamic parameters of the interpolymer reaction between poly-1,1,2-trichlorobuta1,3-diene and poly(ethylene imine) giving a polymer-polymer compound (incorporating the starting components in a molar ratio of 1 : 2) have been determined by calorimetry. The enthalpy (H°_m), entropy (S°_m), and Gibbs function (G°_m) for this reaction are negative over the whole temperature range studied. The enthalpy of the reaction in chloroform at 298.15 K is about two times smaller, due to the difference in the enthalpies of dissolution of the starting polymers and the enthalpy of swelling of the interpolymer in the same solvent. The glass transition temperature of the interpolymer lies between those of the starting polymers and coincides with the value calculated from the Fox equation. The heat capacity of the interpolymer is smaller than additive values calculated fromC _p ^° of the starting polymers. From the experimentally determinedC _p ^° for the polymers, the thermodynamic functionsC _p ^° (T),H°(T) – H°(O), andS°(T) were calculated for the 0–330 K temperature range, and their configurational entropiesS _c ^° were estimated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2474–2478, October, 1996.     

Thermodynamic properties of carbynoid structures in the 0—340 K range

The temperature dependences of the heat capacity (C _p°) of carbynoid structures prepared by alkaline dehydrochlorination of poly(vinylidene chloride) and 1,1,2- and 1,2,3-polytrichlorobutadienes were studied by adiabatic vacuum calorimetry between 5 and 340 K with an accuracy of 0.2%. The low-temperature relaxation transitions and abnormal patterns of the C _p° vs. T dependences were identified and characterized. The experimental results were used to calculate the thermodynamic functions C _p°(T), H°(T) – H°(0), S°(T) – S°(0), and G°(T) – H°(0) for 0—340 K. These data were compared with the corresponding data for carbyne produced by oxidative dehydropolycondensation of acetylene, which is a mixture of amorphous - and -forms with a minor impurity of crystals of both forms.     

Influence of the size of the formed cycle on the reactivity of free radicals in cyclization reactions

Numerous experimental data for the cyclization of free radicals C·H₂(CH₂)_nCH=CH₂ cyclo-[(CH₂)_n+1CH(C·H₂)], and C·H₂(CH₂)_nCH=CHR cyclo-[(CH₂)_n+1C·HCHR] were analyzed in the framework of the parabolic model. The activation energy of thermoneutral (H _e = 0) cyclization E _e0 decreases linearly with an increase in the energy of cycle strain E _rsc: E _e0(n) (kJ mol–1) = 85.5 – 0.44E _rsc(n) (n is the number of atoms in the cycle). The activation entropy of cyclization S ^# also depends on the cycle size: the larger the cycle, the lower S ^#. A linear dependence of S ^# on the difference between the entropies of formation S° of cyclic hydrocarbon and the corresponding paraffin was found: S ^# = 1.00[S°(cycle) – S°(C_nH_2n+2)]. The E _e0 values coincide for cyclization reactions with the formation of the six-membered cycle and the bimolecular addition of alkyl radicals to olefins.     

Thermodynamics of the terpolymer of carbon monoxide,ethylene, and 1-butene

The heat capacity and the temperatures and enthalpies of physical transformations of the alternating terpolymer of carbon monoxide, ethylene, and 1-butene (the content of butene units is 10.7 mol.%) were studied by adiabatic and differential scanning calorimetry in the temperature range from 6 to 520 K. The energy of terpolymer combustion was measured at 298.15 K on an calorimeter with an isothermal shell and static bomb. The standard thermodynamic functions C°_p(T), H°(T)–H°(0), S°(T)–S°(0), and G°(T)–H°(0) for the range from Т → 0 to 400 K, the standard enthalpy of combustion, and the thermodynamic parameters of formation of the partially crystalline CO—ethylene—1-butene terpolymer at 298.15 K, as well as the thermodynamic characteristics of its synthesis in the range from T → 0 to 400 K were calculated.     

Low-temperature heat capacity and high-temperature thermal behavior of sodium lutetium molybdate phosphate Na<Subscript>2</Subscript>Lu(MoO<Subscript>4</Subscript>)(PO<Subscript>4</Subscript>)

The low-temperature heat capacity of Na₂Lu (MoO₄)(PO₄) was measured by adiabatic calorimetry in the range of 7.47–345.74 K. The experimental data were used to calculate the thermodynamic functions of Na₂Lu (MoO₄)(PO₄). At 298.15 K, the following values were obtained: C _p ⁰ (298.15 K) = 237.7 ± 0.1 J/(K mol), S ⁰(298.15 K) = 278.1 ± 0.8 J/(K mol), H ⁰(298.15 K) ? H ⁰ (0 K) = 42330 ± 20 J/mol, and Φ⁰(298.15 K) = 136.1 ± 0. 3 J/(K mol). A heat capacity anomaly was found in the range of 10-67 K with a maximum at T _tr = 39.18 K. The entropy and enthalpy of transition are ΔS = 12.39 ± 0.75 J/(K mol) and ΔH = 403 ± 16 J/mol. The thermal investigation of sodium lutetium molybdate phosphate in the high-temperature range (623–1223 K) was performed using differential scanning calorimetry. It was found that during melting in the range of 1030–1200 K, Na₂Lu(MoO₄)(PO₄) degrades to simpler compounds; the degradation scenario is verified by X-ray powder diffraction.     

Thermodynamics of phenylated polyphenylene between 0 and 340 K

In an adiabatic vacuum calorimeter, the temperature dependence of the heat capacity C _p of phenylated polyphenylene and initial comonomer 1,4-bis(2,4,5-triphenylcyclopentadienone-3-yl)benzene was studied between 6 and 340 K with an uncertainty of about 0.2%. In a calorimeter with a static bomb and an isothermal shield their energies of combustion DUcomb were measured. From the experimental data, the thermodynamic functions C _p ⁰ (T), H ⁰(T)-H ⁰(0), S ⁰(T)-S⁰(0), G ⁰(T)-H ⁰(0) were calculated from 0 to 340 K, and standard enthalpies of combustion ΔH _comb ⁰ and thermodynamic parameters of formation-enthalpies ΔH _f ⁰, entropies ΔH _f ⁰, Gibbs functions ΔG _f ⁰ - of the substances studied were estimated at T=298.15 K at standard pressure. The results were used to calculate the thermodynamic characteristics (ΔH _f ⁰ ,ΔS _f ⁰, ΔG _f ⁰) of phenylated polyphenylene synthesis in the range from 0 to 340 K. This revised version was published online in July 2006 with corrections to the Cover Date.     

A calorimetric study of the thermodynamic properties of potassium molybdate

The low-temperature heat capacity of K₂MoO₄ was measured by adiabatic calorimetry. The smoothed heat capacity values, entropies, reduced Gibbs energies, and enthalpies were calculated over the temperature range 0–330 K. The standard thermodynamic functions determined at 298.15 K were C _p ^° (298.15 K) = 143.1 ± 0.2 J/(mol K), S°(298.15 K) = 199.3 ± 0.4 J/(mol K), H°(298.15 K)-H°(0) = 28.41 ± 0.03 kJ/mol, and Φ°(298.15 K) = 104.0 ± 0.4 J/(mol K). The thermal behavior of potassium molybdate at elevated temperatures was studied by differential scanning calorimetry. The parameters of polymorphic transitions and fusion of potassium molybdate were determined.     

Thermodynamics of cross-linked and branched (co)polymers based on <Emphasis Type="Italic">tris</Emphasis>- and <Emphasis Type="Italic">bis</Emphasis>-(pentafluorophenyl)germanes

The temperature dependence of the heat capacity of cross-linked and branched (co)polymers based on tris- and bis-(pentafluorophenyl)germanes is studied in the temperature range of 6–7 to 535–570 K, using adiabatic vacuum and differential scanning calorimeters. In the indicated temperature range, physical transformations are revealed and their thermodynamic characteristics are determined. The obtained experimental data are used to calculate the thermodynamic functions of (co)polymers: C _p /°, H°(T) - H°(0), S°(T) - S°(0), and G°(T) - H°(0) in the range of T → 0 to 535 K for the branched (co)polymer and from T → 0 to 500 K for the cross-linked polymer. Their standard entropies of formation are determined at 298.15 K. The obtained results are compared with analogous data for hyperbranched perfluorinated polyphenylenegermane studied earlier. The effect of the structure of polyphenylenegermanes on their thermodynamic properties is analyzed.     

Synthesis and magnetism of μ-1,3,5-benzenetricarboxylatocopper(II) trinuclear complexes

Summary Three new Cu^II trinuclear complexes, namely [Cu₃(BZT)(phen)₃(ClO₄)₃]·6H₂O (1), [Cu₃(BZT)(Nphen)₃ (ClO₄)₃]·6H₂O (2) and [Cu₃(BZT)(bipy)₃ (ClO₄)₃]·3H₂O (3) (BZT) = 1,3,5-benzenetricarboxylato, phen = 1,10-phenanthroline, Nphen = 5-nitro-1,10-phenanthroline, bipy = 2,2-bipyridyl, have been synthesized, with 1,3,5-benzenetricarboxylato as the bridged ligand, and characterized by elemental analysis, and i.r. and electronic reflection spectra. We propose that the complexes have an extended 1,3,5-benzenetricarboxylatobridged structure containing three Cu^II atoms. The variable-temperature magnetic susceptibilities of the complexes were measured in the 77–300 K range. The magnetic coupling parameters are consistent with an antiferromagnetic exchange model based on the Hamiltonian operator [=–2J( _{1 2}+ _{1 3}+ _{2 3}, where S ₁=S ₂=S ₃=1/2, giving the antiferromagnetic coupling parameters of 2J = – 18.6 cm^-1 for (1)–(3).     

Thermodynamics of G-3(D4) and G-6(D4) carbosilanecyclosiloxane dendrimers

Temperature dependences of the heat capacity of G-3(D₄) and G-6(D₄) carbosilanecyclosiloxane dendrimers are studied for the first time by precision adiabatic vacuum and differential scanning calorimetry in the range of 6 to 350–450 K. Physical transformations in the investigated temperature range are observed and their standard thermodynamic characteristics are determined and discussed. Standard thermodynamic functions for a mole unit are calculated from the experimental data: C _p ^○ (T), H ^○(T), ? H ^○(0), S ^○(T) ? S ^○(0), and G ^○(T) ? H ^○(0) in the range of T → 0 to (350–449) K and standard entropies of formation at 298.15 K. Low-temperature (T ≤ 50 K) heat capacity is analyzed using the Debye theory of heat capacity of solids and the multifractal model. The values of fractal dimensionality D are determined and some conclusions on the topology of the investigated structures are drawn. The corresponding thermodynamic properties of the investigated carbosilanecyclosiloxane dendrimers under study are compared.     

Thermodynamic properties of graphite-like nanostructures prepared by thermobaric treatment of fullerite C60

Temperature dependences of the heat capacities of disordered graphite-like nanostructures prepared by the thermobaric treatment of fullerite C₆₀ (p = 2 and 8 GPa, T = 1373 K) were measured in the temperature ranges from 7 to 360 K in an adiabatic vacuum calorimeter and from 330 to 650 K in a differential scanning calorimeter. At T < 50 K, the dependences obtained were analyzed using the Debye theory of the heat capacity of solids and its multifractal version. The fractal dimensions D were determined and some conclusions on the heterodynamic character of the structures studied were made. The thermodynamic functions C _p ^o T), H ^o(T) − H ^o(0), S ^o(T) − S ^o(0), and G ^o(T) − H ^o(0) were calculated in the temperature range from T → 0 to 610 (650) K. The thermodynamic properties of the graphite-like nanostructures studied and some carbon allotropes were compared. The standard entropies of formation Δ_f S ^o of the graphite nanostructures studied and diamond were calculated along with the standard entropies of the reactions of their synthesis from the face-centered cubic phase of fullerite C₆₀ and their interconversions at T = 298.15 K. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1940–1945, September, 2008.     

Enthalpy-entropy compensation in ionic micelle formation

The enthalpy-entropy compensation in ionic surfactant micellization process over a large temperature range is examined. The surfactants SDS and C₁₆TAB are investigated experimentally, and the enthalpy and entropy changes are evaluated based on phase separation or mass action models together with the other three surfactant systems. The relationship between compensation temperature and the reference temperatures is discussed.Notations C _p heat capacity change, J/mol-K - CMC critical micelle concentration,M - CMC₀ critical micelle concentration atT=T ₀,M - G Gibbs free energy change, kJ/mol - H enthalpy chang, kJ/mol - h _c enthalpy change for transfer of a methylene group to water, kJ/mol - R gas constant, 8.314 J/mol-K - S entropy change, J/mol-K - S _c entropy change for transfer of a methylene group to water, J/mol-K - S ^* entropy change atT=T ^*, J/mol-K - T temperature,K - T _c compensation temperature, K - T _H temperature at which H=0, K - T ₀ temperature at the minimum point, K - T ^* 112°C Greek Letters degree of dissociation