Synthesis of O-maltosides and O-melibiosides of serine derivatives

Conclusions We synthesized the O-maltosides and O-melibiosides of N-carbobenzoxy-L-serine methylamide and L-serine methylamide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2509–2514, November, 1969.     

Polarizability anisotropy of maleic and phthalic anhydrides

Conclusions The polarizability ellipsoids of the maleic and phthalic anhydride molecules are characterized by substantial nonadditivity.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2154–2156, September, 1977.     

Synthesis of phosphorus-substituted dialkylamides of organophosphorus acids,containing PCH<Subscript>2</Subscript>NP fragments

Reactions of [N-(trimethylsilyl)aminomethyl]phosphonates with organophosphorus acid chlorides was studied, which allowed to develop convenient synthetic approaches to novel phosphorus-substrituted dialkylamides of organophosphorus acids, including a PCH₂NP fragment. Certain properties of the resulting compounds are presented.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 9, 2004, pp. 1422–1425.Original Russian Text Copyright © 2004 by Prishchenko, Livantsov, Novikova, Livantsova, Koval, Grigorev.This revised version was published online in April 2005 with a corrected cover date.     

Radiation trapping in coherent media

We show that the effective decay rate of Zeeman coherence, generated in a (87)Rb vapor by linearly polarized laser light, increases significantly with the atomic density. We explain this phenomenon as the result of radiation trapping. Our study shows that radiation trapping must be taken into account to fully understand many electromagnetically induced transparency experiments with optically thick media.     

Ac-Stark shifts in the nonlinear Faraday effect

The frequency of the dark resonance in coherent population trapping experiments has been measured as a function of the degree of ellipticity and the intensity of the probe light. The results have been used to find the quantum limit of sensitivity of an optical magnetometer based on the nonlinear Faraday effect.     

Algebra with polynomial commutation relations for the Zeeman effect in the Coulomb-Dirac field

We consider a model of particle motion in the field of an electromagnetic monopole (in the Coulomb-Dirac field) perturbed by homogeneous and inhomogeneous electric fields. After quantum averaging, we obtain an integrable system whose Hamiltonian can be expressed in terms of the generators of an algebra with polynomial commutation relations. We construct the irreducible representations of this algebra and its hypergeometric coherent states. We use these states to represent the eigenfunctions of the original problem in terms of the solutions of the model ordinary differential equation. We also present the asymptotic approximations of the eigenvalues in the leading term of the perturbation theory, where the degeneration of the spectrum is removed completely.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 142, No. 1, pp. 127–147, January, 2005.     

Study of Redox-induced Reactions of Vinylidene and bis-Vinylidene Complexes of Manganese

Oxidative dehydrodimerization of some phenylvinylidene complexes of manganese is studied by cyclic voltammetry. In the case of (⁵-C₅H₅)(CO)₂Mn=C=C(H)Ph, the process occurs as the homolysis of the C–H bond in the radical cation of {(⁵-C₅H₅)(CO)₂Mn=C=C(H)Ph}^+· and the dimerization of intermediate -phenylethinyl cation [(⁵-C₅H₅)(CO)₂Mn–CC–Ph]⁺ to a binuclear dication of bis-carbine type (⁵-C₅H₅)(CO)₂Mn⁺C– C(Ph)=C(Ph)–CMn⁺(CO)₂(⁵-C₅H₅). The reduction of the latter leads to binuclear bis-vinylidene complex (⁵-C₅H₅)(CO)₂Mn=C=C(Ph)–C(Ph)=C=Mn(CO)₂(⁵-C₅H₅). Oxidative dehydrodimerization of complexes (⁵-C₅R₅)(CO)(L)Mn=C=C(H)Ph (R = H, L = PPh₃; R = Me, L = CO) occurs through the immediate C–C coupling of radical cations {(⁵-C₅R₅)(CO)(L)Mn=C=C(H)Ph}^+· and yields binuclear dication bis-carbine complexes (⁵-C₅R₅)(CO)(L)Mn⁺C–C(H)(Ph)–C(H)(Ph)–CMn⁺(CO)(L)(⁵-C₅R₅), whose reduction leads to neutral compounds (⁵-C₅H₅)(CO)₂Mn=C=C(Ph)–C(Ph)=C=Mn(CO)(L)(⁵-C₅H₅). Complex (⁵-C₅H₅)(CO)₂Mn=C=C(Ph)–C(Ph)=C=Mn(CO)₂(⁵-C₅H₅) undergoes the oxidation-induced nucleophilic addition of water, forming cyclic bis-carbene product with a bridge heterocyclic ligand (-3,4-diphenyl-2,5-dihydro-2,5-diylidene)-bis-(⁵-cyclopentadienyldicarbonyl manganese).     

Algebra with Quadratic Commutation Relations for an Axially Perturbed Coulomb–Dirac Field

The motion of a particle in the field of an electromagnetic monopole (in the Coulomb–Dirac field) perturbed by an axially symmetric potential after quantum averaging is described by an integrable system. Its Hamiltonian can be written in terms of the generators of an algebra with quadratic commutation relations. We construct the irreducible representations of this algebra in terms of second-order differential operators; we also construct its hypergeometric coherent states. We use these states in the first-order approximation with respect to the perturbing field to obtain the integral representation of the eigenfunctions of the original problem in terms of solutions of the model Heun-type second-order ordinary differential equation and present the asymptotic approximation of the corresponding eigenvalues.     

Low-temperature heat capacity of rare-earth tetraborides

The paper reports an experimental study of the temperature dependences of the heat capacity of tetraborides of lanthanum, dysprosium, holmium, and lutetium in the range 2–300 K. The electronic, lattice, and magnetic contributions to the total heat capacity of the borides have been identified and analyzed, and the Schottky contribution has been calculated. The ground-state multiplicities of dysprosium and holmium ions in the tetraborides have been determined.