A transient two-photon–one-photon double resonance on interband transitions in crystals: I. General relations

A theory of the transient absorption of femtosecond light pulses at a two-photon–one-photon double resonance on adjacent interband transitions in the electronic system has been developed. Approximate expressions for the reactive component of the nonlinear polarization of the three-level system, P _s, which determines the absorbed power in the medium, have been obtained, and the dependences of P _s on the light intensity and detunings of resonances have been calculated.     

Palladium-catalyzed enantioselective 1,3-rearrangement of racemic allylic sulfinates: asymmetric synthesis of allylic sulfones and kinetic resolution of an allylic sulfinate

Described is an asymmetric synthesis of cyclic and acyclic allylic S-aryl and S-alkyl sulfones through a highly selective palladium(0)-catalyzed 1,3-rearrangement of racemic allylic sulfinates. Treatment of racemic cyclic and acyclic allylic S-tolyl- and S-tert-butylsulfinates with Pd(2)(dba)(3).CHCl(3) as precatalyst and N,N'-(1R,2R)-1,2-cyclohexanediylbis[2-(diphenylphosphino)benzamide] as ligand for the palladium atom afforded the corresponding isomeric allylic S-tolyl and S-tert-butyl sulfones of 93-99% ee in 82-96% yield. The rearrangement of the allylic sulfinates most likely proceeds in an intermolecular fashion via formation of a cationic pi-allylpalladium complex and the sulfinate ion. The racemic allylic sulfinates were obtained from the corresponding racemic alcohols and racemic tolylsulfinyl chloride and racemic tert-butylsulfinyl chloride, respectively, in high yields. Rearrangement of the racemic tert-butylsulfinic acid 2-cyclooct-1-enyl ester with Pd(2)(dba)(3).CHCl(3) and the bisphosphane was accompanied by a highly selective kinetic resolution of the substrate and gave at 50% conversion the (R)-configured sulfinate as mixture of the S(S) and R(S) diastereomers of 92% ee and 85% ee and the (S)-configured 3-tert-butylsulfonyl cyclooctene sulfone 15a with 98% ee in almost quantitative yields.     

Calorimetric and dielectric studies of the (NH4)2MoO2F4 oxyfluoride

The temperature dependences of the heat capacity, dielectric properties, and response to an external pressure and an electric field for the (NH₄)₂MoO₂F₄ oxyfluoride (space group Cmcm, Z = 4) have been studied. A comparative analysis of the data on the entropy of phase transitions, p-T phase diagrams, permittivity, and anomalous heat capacity in combination with the results of previous studies of the related compounds (NH₄)₂WO₂F₄ and (ND₄)₂WO₂F₄ has made it possible to establish that both [MO₂F₄]²⁻ anions and ammonium groups play a substantial role in the mechanism and nature of the structural transformations.     

Averaging in parabolic systems,subjected to weakly dependent random perturbations. The L1-approach

One considers an averaging method in equations of parabolic type, situated under the action of centered, weakly dependent random perturbations so that their integrals, normalized in an appropriate manner, satisfy S. N. Bernshtein's exponential estimate. For normalized fluctuations of the solution of the initial equation relative to the solution of the averaged equation, which turns out to be deterministic, one has established S. N. Bernshtein's exponential estimates. On the basis of the obtained inequalities, for an arbitrary prescribed confidence level, one can indicate a confidence band, whose bounds are determined by the solving of the averaged equation, which contains the solution of the initial problem.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 2, pp. 167–172, February, 1991.     

Bernstein inequality under averaging of elliptic systems in periodic random media

We construct the exponential Bernstein inequality for normed fluctuations of a solution of the Dirichlet problem with rapidly oscillating periodic random coefficients with respect to a solution of the averaged Dirichlet problem.     

Structure of the products of radical telomerization of propylene by carbon tetrachloride

Conclusions Isomeric telomerization products of C₃H₆ with CCl₄ with n=3 were isolated, and it was shown by the methods of mass, IR, NQR, and PMR spectroscopy that these isomers are racemates of the two possible diastereoisomers of 1,1,1,7-tetrachloro-3,5-dimethyloctane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1251–1261, June, 1968.The authors are sincerely grateful to I. D. Rubin for taking the PMR spectra and to L. G. Zelenskaya for taking the IR spectra.     

Application of the Gil-Av equation to determine the complexing constant by the gas-chromatographic method

Conclusion The complexing constants, determined by the gas-chromatographic method using the Gil-Av equation, can have either a true or an apparent value, depending on the concentration of the complexing agent and the basicity of the solvent (gas-chromatographic phase).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 441–443, February, 1972.     

BINOL-derived N-phosphino sulfoximines as ligands for asymmetric catalysis

BINOL-derived N-phosphino sulfoximines have been prepared for the first time and tested as ligands in asymmetric transition metal catalysis. Up to 99% ee was achieved in the Rh-catalyzed asymmetric hydrogenation of functionalized olefins and up to 66% ee in the Pd-catalyzed allylic alkylation.     

Solvation-thermodynamic effects of the water-methanol solvent on the coordination of Na+, K+, NH 4 + , and Ag+ ions with 18-crown-6: Gibbs energies of complexation and resolvation of reagents

The results of solvation-thermodynamic monitoring of aqueous-methanol solutions of electrolytes (NaCl, KCl, NH₄Cl, AgNO₃) and 18-crown-6 ether (L) in the mole fraction scale are summarized and systematized. The stability of sodium mono(crown ether) complexes in water-methanol solvents is due to both enthalpy and entropy contributions, and the stability of the ammonium and silver complexes, to the enthalpy contribution. The solvent effects in formation of crown ether complexes of sodium, potassium, ammonium, and silver are subjected to solvation-thermodynamic and correlation analyses. An equation is suggested for estimating the ion selectivity of crown ethers, and the contributions of energy constituents (the Gibbs energy of transfer of reagents) to varation of the ion selectivity of 18-crown-6 toward M-Na⁺ pairs in the water-methanol solvent are revealed.