Crystal structure of bis(5,5-dimethyl-1-hydroxo-4-oxo-2-phenyl-pyrrolin-2-YL-3), recyclization product of 3-imidazoline enaminoketone

Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 3, pp. 145–151, May–June 1994.     

A theoretical study of the structure and thermochemical properties of alkali metal fluoroplumbates MPbF3

Molecular constants of MPbF3 (M=Li, Na, K, Rb, and Cs) were calculated theoretically at the MP2(full) and B3LYP levels with the SDD (Pb, K, Rb, and Cs) and cc-aug-pVQZ (F, Li, and Na) basis sets to determine the thermochemical characteristics of the substances. Satisfactory agreement with experiment was obtained, including the unexpected nonmonotonic dependence of substance dissociation energies on the alkali metal atomic number. The bond lengths of the theoretical CsPbF3 model were substantially elongated compared with experimental estimates, likely because of errors in both theoretical calculations and electron diffraction data processing.     

Synthesis,crystal structure,and properties of [Rh(NH<Subscript>3</Subscript>)<Subscript>5</Subscript>Cl][ReBr<Subscript>6</Subscript>]

A binary complex salt [Rh(NH₃)₅Cl][ReBr₆] has been synthesized and investigated by X-ray diffraction analysis. Crystal data: a = 8.541(5) Å, b = 12.015(6) Å, c = 16.496(9) Å; α = 73.695(10)°, β = 89.746(9)°, γ = 89.676(9)°, V = 1624.7 ų, space group \(P\overline 1 \), Z = 4, D _x = 3.635 g/cm³, R = 0.12. It is shown that the product of thermolysis of the salt in the atmosphere of hydrogen and helium is a solid solution Rh_0.5Re_0.5 with hcp cell parameters a = 2.731(5) Å and c = 4.368(7) Å.     

On preparation of platinum(IV) nitrate solutions from hexahydroxoplatinates(IV)

The parameters of the processes underlying the current technology of preparation of a Pt(NO₃)₄ solution were studied and optimized. The basic problems of the process scheme were determined, including limited storage time of solid hexahydroxoplatinum (IV) acid. Approaches were suggested for increasing the yield and the storage time of intermediate products and for simplifying the conditioning scheme of platinum (IV) nitrate with a significant reduction of time and energy costs.     

Temperature profile and depth of surface melting of a metal irradiated by a high-current ion beam

We have numerically solved the nonlinear thermal conductivity equation using temperature-dependent thermal coefficients to study the evolution of the temperature profile produced in a metal irradiated by a high-current ion beam. We studied the propagation of the thermal front and the heating rate of the metal surface as functions of ion beam characteristics. We determined the dependence of the maximum heating temperature and penetration depth on the maximum value of the ion beam current. Joint Institute for Nuclear Research. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 41, No. 12, pp. 13–20, December, 1998.     

Co-Pt and Fe-Pt bimetallic nanoparticles in a carbon matrix are prepared by a plasma arc process

Nanoparticle ensembles in Co-Pt and Fe-Pt systems embedded in a carbon matrix are prepared by a plasma-arc method. Two-phase samples based on disordered FCC solid solutions are prepared in both systems. In the Co-Pt system, the solid solujtions are mixed within one ensemble; in the Fe-Pt system, they are spatially separated. A magnetization hysteresis curve from Co-Pt nanoparticles (3–12 nm) fully coincides with a magnetization curve from a single-phase disordered solid solution Co_0.50Pt_0.50 (7–9 nm) prepared at 325°C by thermolysis of the precursor double complex salt (DCS). Metal ratios, solid solution structures, and particle sizes being the same, the magnetic response is dictated exclusively by the amount of a magnetic phase of mixed and interacting particles and is independent of the distribution of the magnetic phase over the solid solution phases.     

TETRAAMMINOPLATINUM(II) PARAMOLYBDATE. SYNTHESIS,CRYSTAL STRUCTURE,THERMAL PROPERTIES

Journal of Structural Chemistry - The crystal structure of the [Pt(NH3)4]3Mo7O24·5.5H2O complex salt is determined for the first time by XRD. Thermal decomposition of this complex in reducing...     

APPLICATION OF N-DOPED CARBON NANOTUBES FOR THE PREPARATION OF HIGHLY DISPERSED PdO–CeO2 COMPOSITE CATALYSTS

Journal of Structural Chemistry - Pd–CeO2 catalytic composites deposited on the surface of carbon nanomaterials (CNMs) can act as model systems for probing the nature of active sites of...     

Long electron spin memory times in gallium arsenide

Extremely long electron spin memory times in GaAs are reported. It was established by the optical orientation method that the spin relaxation time of electrons localized at shallow donors in n-type gallium arsenide (N _d ?N _A ≈10¹⁴ cm^?3) is 290±30 ns at a temperature of 4.2 K. The exchange interaction of quasi-free electrons and electrons at donors suppresses the main spin-loss channel for electrons localized at donors—spin relaxation due to the hyperfine interaction with lattice nuclei.