[en] Using the Knudsen method with mass-spectral analysis of gaseous phase, formation enthalpies of gaseous anions MF₃X^- (M=Al, Ga; X=Cl, Br, I), which constitute Δ_fH₀⁰ (AlF₃Cl^-)=-1726±15, Δ_fH₀⁰ (AlF₃Br^-)=-1674±15, Δ_fH₀⁰ (AlF₃I^-)=-1612±15, Δ_fH₀⁰ (GaF₃Cl^-)=-1397, Δ_fH₀⁰ (GaF₃Br^-)=-1335±30, Δ_fH₀⁰ (GaF₃I^-)=-1290±30 kJ/mole, have been determined (MF₃-X^-) bond breaking energies are calculated

[en] Complete text of publication follows. Mechanisms of reactions under the influence of light on the methyloxirane (MO) radical cations (RC) obtained by xray irradiation and stabilized in freonic matrices at 77 K are investigated by the ESR and UV-VIS spectroscopy as well as quantum chemistry (TD DFT, PBE1). The positions of two peaks in the UV-visible spectra are similar in both freons (λ₁ ∼ 435 nm for < band 1> and 530 nm for < band 2>). The absorption coefficients are estimated to be 1.9 l/(mol cm) and 3.3 l/(mol cm) respectively, while the quantum yields of the reactions taking place under the influence of light (λ₁ = 436 nm and λ₂ = 546 nm) are approximately ψ = 0.03 and ψ = 0.02. As direct measurement of the hyperfine couplings in the ESR spectra proved problematic due to the complicated spectra, modeling of the spectra was carried out. The modeling was based on the results of the TD DFT calculations with further optimization for the better accommodation of experimental results, the most intriguing of which is the rather large doublet coupling constant arising in the ESR spectra corresponding to the 435 nm peak in the UV-VIS spectra. It's also necessary to mention that the quantum chemical calculations predict potential minima for two < ring-closed> forms for the MO RC (differentiated by the C-C bond length: 1.46 A versus 1.72 A which is the one with the large doublet coupling) as well as two < ring-open> forms. With the modeling being successful in separating individual experimental spectra attributed to three different forms of the MO RC it is discovered that the conclusions of Shida et al. are erroneous and the interpretation of the reversible photoinduced changes as cis-trans isomerisation of the < ring-open> forms of the RC must be substituted with an explanation taking a process that involves the < ring-closed> forms into account. ESR spectrum with the large doublet due to the < ring-closed> form with a longer C-C bond which arise from photochemical excitation (as opposed to the other cyclical form that doesn't exist at T 77 K) while the original spectrum observed immediately after irradiation is attributed to the mixture of the < ring-open> forms of the RC. The work was supported by the grant of RFBR (07-03-00105) and the program of Presidium of RAS ChD-01.

[en] The gaseous phase of the system LiF-HfF₄ is investigated by means of isothermal evaporation. Using experimental data, p-X diagrams are constructed for 1125, 1075, 1025, 975 and 925 K. It is shown that the azeotrope with minimum total pressure observed at 1125 K degenerates upon lowering of the temperature and entry into the heterogeneous region. At 975 K the azeotrope corresponds to the point of inflexion from the horizontal tangent on the total pressure curve. At lower temperatures azeotropic distillation is absent from the system. (author)

No abstract available

No abstract available

No abstract available

[en] Knudsen's method with mass spectral analysis has been applied to study equilibria in saturated vapor in the NaI-DyI₃ and CsI-HoI₃ systems. Enthalpies of reactions with participation of positive ions are calculated. Enthalpies of ion formation δ_fH₂₉₈ are determined. They are: Na₂I⁺(370+-15), Na₃I₂⁺(116+-17), Cs₃I₂(-140+-17), NaDyI₃⁺(124+-16), CsHoI₃⁺(44+-16), Na₂DyI₄⁺(-125+-25), Na₃DyI₅⁺(-406+-27kJ/mol)

No abstract available

No abstract available

[en] The mass-spectrometric method has been used to investigate equilibrium between neutral and charged particles in the saturated vapour of the KF-ScF₃ (T approximately 1050 K) system. Formation heats (ΔHsub(f,298)sup(0)) of ScF₄-, KF₂-, and AlF₄- negative ions are determined, which are -2008.8+-12.6; -806.3+-11.3 and -1969.5+-12.6 kJ/mol respectively