Thermal Properties of Cobalt(II) β-Iminoketonates

Russian Journal of General Chemistry - Thermogravimetry, differential scanning calorimetry, and flow methods were used to investigate thermal properties of a series of cobalt(II)...     

Thermodynamic study of a series lithium β-diketonates

Thermal behaviour of a series of lithium β-diketonates: Li(dpm) (dpm=dipivaloylmethanate (2,2,6,6-tetramethylheptane-3,5- dionate)), Li(pta) (pta=pivaloyltrifluoracetonate (2,2-dimethyl-6,6,6-trifluoro-3,5-hexanedionate)), Li(tfa) (tfa=trifluoracetylacetonate (1,1,1-trifluoro-2,4-pentandionate)), Li(hfa) (hfa=hexafluoracetylacetonate (1,1,1,5,5,5-hexafluoro-2,4-pentandionate)) has been investigated. Gas phase composition of these complexes has been established. Temperature dependences of vapor pressure of lithium compounds were obtained by static and dynamic methods, and thermodynamic parameters were calculated. Dependence of compound volatility on ligand structure is shown. For Li(dpm) detailed investigation has been done by differential scanning calorimetry (DSC).     

Complexation of citric and tartaric acids with Na and K ions in aqueous solution

The formation of MTar^–, MCit^2– and M₂Cit^– complexes (M is Na⁺ or K⁺) was established in reactions of aqueous solutions of citric and tartaric acids with sodium or potassium chloride solutions; their stability constants were determined by potentiometric titration in aqueous solution at 298.15 K and ionic strength 0.1 and 0.3 mol/l with tetraethylammonium chloride (TEACl) as a supporting electrolyte. Heat effects of reactions between citric acid solutions and sodium or potassium chlorides were measured by calorimetric method at 288.15, 298.15, and 308.15 K and at the ionic strength 0.1, 0.2, and 0.3 M TEACl. The increasing ionic strength was found to decrease exothermic effect of complex formation processes, while the temperature produced the opposite effect. Extrapolation to zero ionic strength was used to find thermodynamic stability constants and standard heat effects of complex formation reactions in solutions of oxyacids. The changes in entropy and heat capacity were calculated as well as standard enthalpies of formation of Na and K complexes of the indicated oxyacids in aqueous solution at 298.15 K.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 4, 2005, pp. 253–261.Original Russian Text Copyright © 2005 by Zelenina, Zelenin.     

Tensimetric Study of the Tris(2,2,6,6-tetramethylheptan-3,5-dionato)yttrium(III) Dissociation in a Gas Phase

Russian Journal of General Chemistry - The saturated and unsaturated vapor pressures of tris(2,2,6,6-tetramethylheptane-3,5-dionato)yttrium(III), Y(thd)3, were measured by the static method with a...     

Thermal properties of volatile ruthenium(III) complexes

Complexes of ruthenium(III) with the following beta-diketone derivatives: 2,4-pentanedione (Ru(acac)₃), 1,1,1,6,6,6-hexafluoro-2,4-pentanedione (Ru(hfac)₃), and 2-methoxy-2,6-dimethyl-3,5-heptanedione (Ru(mdhd)₃) were synthesized, purified, and identified by chemical analysis and melting points. By difference-scanning calorimetry (DSC) in vacuum the thermodynamic characteristics of melting processes were defined. Using the static method with quartz membrane zero-manometer, the temperature dependencies of saturated and unsaturated vapor pressure were obtained for Ru(hfac)₃. The standard thermodynamic characteristics of vaporization processes enthalpy ?H _T* and entropy ?S° _T* were determined.     

Heat effect of pulsed laser radiation on the real structure of CdTe single crystals

Real structure modification of CdTe single crystals exposed to pulsed radiation of ruby and Nd: YAG lasers is investigated using X-ray diffraction topography in the reflection configuration. The changes are mostly due to effects of heat in a thin surface layer. Depending on the incident laser energy, the following significant changes in the real structure of the crystal surface layer are observed: (1) integral improvement of the surface structure due to microstress relaxation; (2) the formation, development, and degradation of an ordered twin structure in the process of recrystallization; and (3) the formation of a fine-mesh dislocation structure. All these changes barely affect the bulk of the crystal. Mechanisms of the modifications are discussed, along with possibilities for their monitoring and control.     

One-dimensional deformations of nonlinearly elastic micropolar bodies

We find families of finite deformations of a Cosserat elastic continuum on which the system of equilibrium equations is reduced to a system of ordinary differential equations. These families can be used to describe the expansion, tension, and torsion of a hollow circular cylinder, cylindrical bending of a rectangular slab, straightening of a circular arch, reversing of a cylindrical tube, formation of screw and wedge dislocations in a hollow cylinder, and other types of deformations. In the case of a physically nonlinear material model, the above-listed families of deformations can be used to construct exact solutions of several problems of strong bending of micropolar bodies.     

The Nonlinear Theory of Quasi-Solid States of Micropolar Elastic Bodies

Doklady Physics - A nonlinear theory of quasi-solid states of micropolar elastic bodies is proposed. Quasi-solid states are a three-dimensional analog of the surface bending and are possible only...