Heterogenized transition metal complexes as catalysts for synthesizing methylpyridines from acetaldehyde and ammonia

The synthesis of methylpyridines from acetaldehyde and ammonia in the presence of N- and F-containing heterogenized transition metal complexes is studied by a pulse microcatalytic method. A correlation between the donor—acceptor properties of the ligand, of the complexed metal, and of the catalytically active complex is found using ³¹P NMR. The reaction direction depends on the properties of the solvent used to heterogenize the complex on the carrier.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 773–779, June, 1993.     

A mixed domain structure in ferrite-garnet films

A stable static mixed domain structure consisting of strip domains and a cylindrical magnetic domain (CMD) is obtained in (Bi_0.7Lu_0.3)₃ (Fe_0.8Ga_0.2)₅ O₁₂ ferrite-garnet films. An analytic theory of the mixed domain structure is constructed. An analytic solution is obtained for the shape of a distorted strip domain, which is in good agreement with experimental results.     

EPR spectroscopy of quintet 4-amino-3,5-dichloropyridine-2,6-diyldinitrene isolated in solid argon

An EPR spectrum of solid Ar isolated quintet 4-amino-3,5-dichloropyridin-2,6-diyldinitrene that formed by the photolysis of 4-amino-2,6-diazido-3,5-dichloropyridine at 15 K was recorded. Using computer simulation based on numerical diagonalization of the quintet spin Hamiltonian matrices, it was established that this EPR spectrum corresponds to a quintet spin state with the magnetic parameters g = 2.0023, |D _q| = 0.2100 cm⁻¹, and |E _q| = 0.0560 cm⁻¹. Owing to high resolution of the experimental spectrum, the zero-field splitting parameters of the quintet intermediate were determined to an accuracy of at least 5·10⁻⁴ cm⁻¹. Calculations of the fine-structure energy levels in external magnetic field and the dependences of the EPR signal positions and intensities of the quintet dinitrene on the direction of external magnetic field were performed for the first time. This allowed unambiguous assignment of all EPR lines of quintet molecules having both in-principal-axis and off-principal-axis orientations. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2284–2289, December, 2007.     

Triterpene and steroid glycosides of the genusMelilotus and their genins IV. Trillin and dioscin from the seeds ofMelilotus tauricus

Two steroid glycosides belonging to the spirostan series — trillin and dioscin — have been isolated from the seeds of the plantMelilotus tauricus (Bieb.) Ser.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 770–772, November–December, 1994.     

Triterpene and steroid glycosides of the genusMelilotus and their genins II. Melilotoside D from the roots ofMelilotus albus

A new triterpene glycoside of the oleanane series — melilotoside D — has been isolated from the roots of plantMelilotus albus Medik. (Leguminosae). Melilotoside D is a tetraoside of soyasapogenol B. Its structure has been shown on the basis of chemical transformations and spectral characteristics as soyasapogenol B 3-O-{[O-α-L-rhamnopyranosyl-(1→2)]-[O-α-L-arabinopyranosyl-(1→3)]-O-β-D-galactopyranosyl-(1→2)-α-L-arabinopyranoside}.     

Synthesis and structures of 2,3,6-triaryl-1-acyl-4-acyloxypiperideines

1-Acyl-4-acyloxy-2,3,6-triaryl-³- and ⁴-piperideines were obtained by acylation of 2,3,6-triarylpiperidone and its 1-acetyl derivative with carboxylic anhydrides and chlorides. The molecular and crystal structures of 3-phenyl-2,6-bis(o-acetoxyphenyl)-1-acetyl-4-acetoxypiperidin-3-ene were established by x-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1352–1358, October, 1990.     

Electron and donor-impurity-related Raman scattering and Raman gain in triangular quantum dots under an applied electric field

The differential cross-section of electron Raman scattering and the Raman gain arecalculated and analysed in the case of prismatic quantum dots with equilateral trianglebase shape. The study takes into account their dependencies on the size of the triangle,the influence of externally applied electric field as well as the presence of an ionizeddonor center located at the triangle’s orthocenter. The calculations are made within theeffective mass and parabolic band approximations, with a diagonalization scheme beingapplied to obtain the eigenfunctions and eigenvalues of the x-y Hamiltonian. The incidentand secondary (scattered) radiation have been considered linearly-polarized along they-direction, coinciding with the direction of theapplied electric field. For the case with an impurity center, Raman scattering with theintermediate state energy below the initial state one has been found to show maximumdifferential cross-section more than by an order of magnitude bigger than that resultingfrom the scheme with lower intermediate state energy. The Raman gain has maximum magnitudearound 35 nm dot size andelectric field of 40 kV/cm forthe case without impurity and at maximum considered values of the input parameters for thecase with impurity. Values of Raman gain of the order of up to 10⁴cm^-1 are predicted in bothcases.     

Grain Structure Formation in Ni3Al Intermetallic Compound Synthesized Under High-Temperature and Pressure Conditions

Russian Physics Journal - The paper presents theoretical and experimental results of studying the grain structure formation of the Ni3Al intermetallic compound produced by self-propagating...