Integral intensities of absorption bands of silicon tetrafluoride in the gas phase and cryogenic solutions: Experiment and calculation

The spectral characteristics of the SiF₄ molecule in the range 3100–700 cm^?1, including the absorption range of the band ν₃, are studied in the gas phase at P = 0.4–7 bar and in solutions in liquefied Ar and Kr. In the cryogenic solutions, the relative intensities of the vibrational bands, including the bands of the isotopically substituted molecules, are determined. The absorption coefficients of the combination bands 2ν₃, ν₃ + ν₁, ν₃ + ν₄, and 3ν₄ are measured in the solution in Kr. In the gas phase of the one-component system at an elevated pressure of SiF₄, the integrated absorption coefficient of the absorption band ν₃ of the ²⁸SiF₄ molecule was measured to be A(ν₃) = 700 ± 30 km/mol. Within the limits of experimental error, this absorption coefficient is consistent with estimates obtained from independent measurements and virtually coincides with the coefficient A(ν₃) = 691 km/mol calculated in this study by the quantum-chemical method MP2(full) with the basis set cc-pVQZ.     

Field and frequency-dependent dielectric constant of quasi-one-dimensional semiconductors

The “conducting box” polarization model proposed by the present author and Belyantsev [4] which explains successfully the value and the frequency dependence of the giant dielectric constant of the one-dimensional organic semiconductor Me φ₃ As(TCNQ)₂, predicts that the dielectric constant drops in the high-electric-field region. The typical electric field strength is of the order of 20 V cm^?1.     

Study of the products of the reaction of succinic anhydride derivatives with urea

Conclusions The product of the reaction of isododecenylsuccinic anhydride with urea at 120–160°C is isododecenylsuccinimide.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1900–1902, August, 1988.     

Structure of O-semiquinolate complexes of tin and titanium trifluorides

Conclusions The interaction of substituted o-benzoquinones with tin and titanium tetrafluorides leads to the formation of the o-semiquinolate complex of the corresponding metal trifluoride. The tin-containing complexes exist in two forms of an octahedral structure differing in the mutual location of the added ligands; the ratio of these forms depends on the nature of the solvent. The titanium-containing complexes are obtained in a single form, owing to the different ligand repulsion energy when the size of the central atom is changed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2002–2009, September, 1984.     

Adsorption of solvent and oxidant molecules on magnesium surface: effect on the electronic structure and reactivity of magnesium in reactions of Grignard reagent formation

The effect of adsorption of the oxidant (EtBr) and aprotic dipolar solvent molecules on the electronic structure and properties of Mg _n (n ≤ 50) clusters simulating the surface of metallic magnesium was studied by the B3PW91/6-31G(d) density functional method. It was found that the work function of an electron from the cluster monotonically decreases as the donor ability of the adsorbed molecules increases. The experimentally measured rate of the magnesium oxidation by EtBr correlates with the negative Mulliken charge density of the first coordination sphere of the surface adsorption site. The results obtained are in agreement with the experimentally determined work function of electron from metals during adsorption from the gas phase. Presumably, the rate-limiting step of the Grignard reagent formation is the surface oxidation reaction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 458–469, March, 2008.     

IR spectroscopic andab initio quantum-chemical study of the products of hydrolysis of silicon tetrafluoride at low water concentrations

According to the results of IR spectroscopic study and quantum-chemical calculations, hydroxo derivatives SiF_4-x(OH)_x are formed in the course of hydrolysis of silicon tetrafluoride in the presence of small amount of water along with hexafluorodisiloxane. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–96, January, 1999.     

Theoretical study of the structures of [M(18C6)](HFA)2 complexes (M = Ba,Sr, Pb,Cd, Mn; 18C6 = 18-crown-6; HFA = hexafluoroacetylacetonate anion)

The structures of the [M(18C6)]²⁺ cations (M = Ba, Sr, Pb, Cd, Mn) and their salts [M(18C6)](HFA)₂ and [M(18C6)](NO₃)₂ have been calculated by the density functional theory method (in the B3LYP/6-311++G** + LanL2Dz approximation). Upon geometry optimization, the gas-phase structures of compounds of different composition have been calculated; for them, the strength of binding of the central cation to the crown ether (18C6) and the degree of structural similarity have been evaluated. The structure of the [NH₄(18C6)]⁺ cation identified in a practical synthesis has also been considered. For metal cations acting as a central atom, NH ₄ ⁺ and [M(18C6)]²⁺ complex cations, as well as for intermediate and ultimate products [M(18C6)](NO₃)₂ and [M(18C6)](HFA)₂ (M = Ba, Sr, Pb, Cd, Mn), the electronic chemical potential and Pearson hardness, which enables the consideration of the propensity of various reagents to interact with each other in terms of the empirical HSAB principle (hard with hard and soft with soft), have been evaluated. Comparison of the estimates with the properties of the synthesized compounds with M = Ba, Sr, and Pb makes it possible to preliminarily verify the applicability of this principle to the systems under consideration and predict some properties of isostructural analogues important in the search for methods of synthesis of [M(18C6)](HFA)₂, where M = Cd and Mn. The possibility of establishing a correlation between the electron density of the system, stability, and hydrolytic activity of complexes has been shown.     

Doping of boron carbides with cobalt, using cobaltocene

The decomposition of cobaltocene under low energy electron irradiation appears facile, and evidence suggests that the decomposition products lead to an increase in the carrier concentration in semiconducting boron carbides. Using cobaltocene to introduce dopants, we fabricated a semiconducting boron carbide homojunction PACS 81.05.Je; 81.15.Gh; 61.72.Ww; 82.33.Ya     

Monte-Carlo generator for e+e- annihilation into lepton and hadron pairs with precise radiative corrections

Recently, various cross sections of e⁺e^- annihilation into hadrons were accurately measured in the energy range from 0.37 to 1.39 GeV with the CMD-2 detector at the VEPP-2M collider. In the π⁺π^- channel a systematic uncertainty of 0.6% has been achieved. A Monte-Carlo Generator Photon Jets (MCGPJ) was developed to simulate events of Bhabha scattering as well as production of two charged pions, kaons and muons. Based on the formalism of structure functions, the leading logarithmic contributions related to the emission of photon jets in the collinear region are incorporated into the MC generator. Radiative corrections (RC) in the first order of α are accounted for exactly. The theoretical precision of the cross sections with RC is estimated to be better than 0.2%. Numerous tests of the program as well as a comparison with other MC generators and CMD-2 experimental data are presented.