Теплоемкость трис-гептафтордиметилоктандионата лантана (La(C10H10F7O2)3; CAS номер: 19106-89-9) измерена адиабатическим методом в интервале от 10.88 K до 300.60 K. На основе полученных данных вычислены значения термодинамических функций (энтропия, приращение энтальпии и приведенная энергия Гиббса) в интервале температур от 0 K до 300 K. В результате проведенного анализа функционального поведения теплоемкости выявлена аномалия в интервале 36 – 110 K с максимумом при температуре Т ≈ 80 K, которая указывает на наличие фазового перехода в данном диапазоне температур. Выделены аномальные вклады в энтропию и энтальпию. Рассматривается возможная причина обнаруженного фазового перехода.

Heat capacity of tris-lanthanum heptafluorodimethyloctanedionate (La(C10H10F7O2)3; CAS no. 19106-89-9) has been measured by the adiabatic method in the range from 10.88 to 300.60 K. Based on the data obtained, the values of thermodynamic functions (entropy, enthalpy increment, and reduced Gibbs energy) have been calculated in the temperature range from 0 to 300 K. As a result of the analysis of the functional behavior of the heat capacity, an anomaly has been revealed in the range of 36–110 K with a maximum at temperature T ≈ 80 K, which indicates the presence of a phase transition in this temperature range. Anomalous contributions to entropy and enthalpy are identified. The possible cause of the detected phase transition has been considered.

Представлены результаты исследования монокристалла дивольфрамата натрия на основе полученных экспериментально данных о теплоемкости. Теплоемкость Na2W2O7 измерена методом релаксационной калориметрии в интервале 1.9–220 K. Аномалий в теплоемкости, связанных с фазовыми переходами, не обнаружено. Выполнена экстраполяция теплоемкости к 0 K, и определена температура Дебая при нуле. На основе экспериментальной теплоемкости рассчитаны термодинамические функции: энтропия, приращение энтальпии и приведенная энергия Гиббса.

The results of a study of a sodium ditungstate single crystal based on the experimental heat capacity data are presented. The heat capacity of Na2W2O7 was measured by relaxation calorimetry in the range 1.9‒220 K. No anomalies in the heat capacity associated with phase transitions were detected. The heat capacity was extrapolated to 0 K, and the Debye temperature at 0 K was determined. The thermodynamic functions (entropy, enthalpy increment, and reduced Gibbs energy) were calculated from the experimental heat capacity.

Bismuth cobalt dysprosium oxide of composition Bi12.5Dy1.5CoO22.325 has been prepared by solid-state reactions. The compound has a cubic structure (space group Fm 3̅ m) with the unit cell parameter a = 0.55279(5) nm. The solution enthalpy and standard enthalpy of formation of Bi12.5Dy1.5CoO22.325 have been measured by solution calorimetry: ΔsolH0 = −1017.0 ± 7.5 kJ/mol, and ΔfH0 = −5338.8 ± 19.9 kJ/mol. The lattice enthalpy has been calculated using the Born–Haber cycle: ΔlatH0 = −99020 kJ/mol. The lattice enthalpy increases in magnitude as the lanthanide radius decreases in the neodymium–dysprosium–holmium series.

Министерство науки и высшего образования Российской Федерации Российское химическое общество им.Д.И.Менделеева Секция по химической термодинамике и термохимии Научного совета РАН по физической химии Сибирское Отделение Российской Академии Наук Институт неорганической химии им.А.В.Николаева СО РАН

A variety of physicochemical means are used to synthesize and characterize a sample of the dimer lutetium pivaloyltrifluoroacetonate ([Lu(C 8 H 10 F 3 O 2 ) 3 ] 2 ) complex. The thermal stability of this complex is studied via differential thermal analysis (DTA) and thermogravimetry (TG) in the region of 300–505 K, and its temperature of melting is determined. Experimental heat capacity data are measured in the region of 195‒410 K for the first time via differential scanning calorimetry. No heat capacity anomalies associated with phase transitions are revealed below the melting point. Smoothed values are calculated for the regular heat capacity of [Lu(C 8 H 10 F 3 O 2 ) 3 ] 2 in the region of 195–443 K.

The heat capacity of cobalt trisdipivaloyl methanate Co(C 11 H 19 O 2 ) 3 was measured by the adiabatic method within the temperature range 8.18–301.61 K. The analysis of the functional dependence of the heat capacity did not revealed any thermal anomalies in its behavior. The thermodynamic functions (entropy, enthalpy, and reduced Gibbs energy) were calculated from the measured experimental data on the heat capacity within a temperature range of 0–300 K. The absolute entropy was used to calculate the formation entropy of Co(C 11 H 19 O 2 ) 3 at Т = 298.15 K.

Physicochemical study of cis -[Pt(NH3)2Cl2] and cis -[Pt(NH 3 ) 2 Cl 2 (OH) 2 ] is carried out, and immobilization of platinum complexes on the nanoporous carbon substrate is investigated. The solubility of cis -[Pt(NH 3 ) 2 Cl 2 ] in 1 M HCl solution is determined, and the average enthalpy of dissolution is calculated: Δ sol H ° = 27.3 ± 0.9 kJ/mol. The batch capacity is determined experimentally for cis-[Pt(NH3)2Cl2] and cis- [Pt(NH 3 ) 2 Cl 2 (OH) 2 ] to be 32.9 mg/g (0.17 mg-equiv/g) and 47.6 mg/g (0.24 mg-equiv/g), respectively. Immobilization of platinum complexes on the oxidized carbon surface is found to take place due to interaction between carboxy groups and ammine groups of platinum complexes. The resulting heat capacity curves are used to calculate the enthalpies of adsorption for cis -[Pt(NH 3 ) 2 Cl 2 ] and cis-[Pt(NH 3 ) 2 Cl 2 (OH) 2 ] on the oxidized carbon surface, equal to 24.46 and 27.46 kJ/mol, respectively.

Three novel carboxylate complexes were synthesized: dimethylgold(III) trifluoroacetate [Me 2 Au(Tfa)] 2 ( I ), trimethylacetate (pivalate) [Me 2 Au(Piv)] 2 ( II ), and benzoate [Me 2 Au(OBz)] 2 ( III ). The starting reagent was [Me 2 AuI] 2 . The procedure of its synthesis provides 60% product yield. Dimethylgold(III) carboxylates were identified from the IR and 1 H NMR data. The title compounds were studied by X-ray diffraction. The unit cell parameters for I, C 8 H 12 Au 2 F 6 O 4 : a = 15.5522(13), b = 12.9398(11), c = 15.6555(14) Å, β = 104.308(2)°, Z = 8, ρ(calcd.) = 2.959 g/cm 3 , space group C 2/ c , R = 0.0779; for II , C 14 H 30 Au 2 O 4 : a = 10.3025(3), b = 15.5952(4), c = 12.6819(3) Å, β = 105.8270(10)°, Z = 4, ρ(calcd.) = 2.224 g/cm 3 , space group P 2 1 / c , R = 0.0229; for III , C 18 H 22 Au 2 O 4 : a = 12.8050(2), b = 19.7886(3), c = 7.60300(10) Å, Z = 4, ρ(calcd.) = 2.401 g/cm 3 , space group Pnma, R = 0.0144. Compounds I–III have the molecular structures; the structural units are the [(CH 3 ) 2 Au(OOCR)] 2 dimers (Au…Au 2.984–3.080 Å), R = CF 3 , tert -Bu, Ph. The gold atoms have the square coordination with two carbon atoms and two oxygen atoms (Au-O 2.120–2.173 Å). The molecules in compounds I–III are united into infinite unidimensional chains connected by van der Waals interactions.

Dimethylgold(III) complexes with 8-hydroxyquinoline Me 2 Au(Ox) ( I ) and 8-mercaptoquinoline Me 2 Au(Tox) ( II ) were synthesized and studied. Complex II obtained for the first time was identified from the elemental analysis, IR, 1 H NMR, and mass spectrometry data. The thermal properties of complexes I, II in condensed state were investigated by thermography. The temperature dependences of the saturated vapor pressure over crystals were measured by the Knudsen effusion method with mass spectrometric recording of the gas phase composition and the thermodynamic characteristics of the sublimation process were determined: for I , log P [Torr] = (14.6 ± 0.3) − (6.34 ± 0.10) × 10 3 /( T , K), Δ H subl o = 121.2 ± 1.9 kJ −1 , Δ S subl o = 224.1 ± 4.6 J mol −1 K −1 (the temperature interval under study 80–115°C); for II , log P [Torr] = (13.3 ± 0.2) − (6.30 ± 0.09) × 10 3 /( T , K), Δ H subl o = 120.5 ± 1.7 kJmol −1 , Δ S subl o = 199.3 ± 3.0 J mol −1 K −1 (86–145°C).