A Bernasconi model for constructing ground-state spin systems

A Bernasconi model for a one-dimensional chain of quantum particles is considered. It is shown that searching for the ground state of such a quantum system is equivalent to searching for binary sequences with minimum energy levels of the side lobes of the aperiodic autocorrelation function (ACF). A review and new results regarding the construction of such binary sequences are presented.     

A Study on the phase transition in decamethylosmocene crystal over a wide temperature range

The reversible structural phase transition accompanied by the doubling of the unit cell parameter c and a change in the space group is found in the decamethylosmocene crystal Cp ₂ ^* at a temperature of 243 ± 5 K. In the high-temperature (HT) phase (space group P2₁/m, Z = 2), the molecule adopts an eclipsed conformation and lies in the mirror symmetry plane. In the low-temperature (LT) phase (space group P2₁/c, Z = 4), the molecule occupies the general position with a small rotation of the ligands. The structural transformations from the high-temperature phase into the low-temperature phase at 120 K are described by the deviation of the molecular axis of fivefold symmetry by 3.2(2)° and the displacement of the center of mass of the molecule by 0.173(2) Å with respect to their positions in the high-temperature phase, and also by the rotation of the Cp* ligands in the same direction by 3.0(2)° and 5.4(2)°, respectively.     

Crystal structure of phenylhydrazine with diacetyl substituted ketol of the cyclohexane series

The reaction of 2,4-diacetyl-5-hydroxy-5-methyl-3-phenylcyclohexanone-1 with phenylhydrazine is conducted, and the crystal structures of its products, 1-(6-hydroxy-3,6-dimethyl)-2,4-diphenyl-4,5,6,7-tetrahydro-2H-indazol-5-yl)ethane-1-one and 1-(2-hydroxy-2-methyl-6-phenyl-4-(2-phenylhydrazono)-5-(1-(2-henylhydrazono)ethyl)cyclohexyl)ethane-1-one, are determined by single crystal XRD.     

Formation of low-valence palladium species in the course of oxidation of alcohols with palladium(II) tetraaqua complex

The formation of low-valence palladium species Pd _n ²⁺ (n ≥ 2) in the course of oxidation of aliphatic C₁-C₄ alcohols with oxygen in the presence of palladium(II) tetraaqua complex in aqueous solution was proved UV-spectrophotometrically by the absorption band with a maximum at 312 or 316 nm depending on particular alcohol.     

Crystal structure of 3-amino-5-acetyl-4,7-dihydro-6-methyl-4-(2-nitrophenyl)-2-cyanothieno[2,3-b]-pyridine and specific features of its molecular packing in crystal

The molecular and crystal structures of 3-amino-5-acetyl-4,7-dihydro-6-methyl-4-(2-nitrophenyl)-2-cyanothieno[2,3-b]-pyridine is determined by X-ray diffraction. The unit-cell parameters are as follows: a = 14.68(1) Å, b = 8.704(5) Å, c = 25.36(1) Å, V = 3241(6) ų, d _calcd = 1.453 g/cm³, Z = 8(1,1), and space group Pna2₁. Theo-nitrophenyl substituent is synperiplanar relative to the hydrogen atom at the C(4) atom of the heterocycle. Two crystallographically independent reference molecules A and B in the structure can be considered a pair of the enantiomers related by an approximate noncrystallographic center of inversion. The degree of approximation of this pseudocenter is discussed. It is shown that the structure can be described as a combination of two systems of translationally equal layers. The pseudosymmetry of the crystal structure and the possibility of forming a similar molecular packing with a higher crystallographic symmetry are considered.     

Optimization of the Pyrolysis of Naphtha Fractions of the West Siberian Gas Condensate to Obtain Lower Olefins and Divinyl

Russian Journal of Applied Chemistry - Naphtha fractions of the West Siberian gas condensate were evaluated as feedstock for thermal pyrolysis performed in the temperature interval...     

Reaction of thiiranes with azomethine compounds

Thiiranes add to imines and oximes to give thiazolidines. The addition of asymmetrical thiiranes is regioselective. The reaction of derivatives of asymmetrical carbonyl compounds with methylthiirane leads to mixtures of cis and trans stereoisomers of thiazolidines. In the N-arylideneethylamine series the reaction is accelerated by donor substituents and is retarded by acceptor substituents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 627–633, May, 1982.     

Kinetics of Reaction between Oxygen and Hydrogen in Water in the Presence of Pd(0)-containing Compounds

Kinetic features of the reaction of oxygen with hydrogen in water in the presence of colloidal palladium in situ, palladium black, and the giant Pd cluster Pd_{5 6 1}Phen_{6 0}(OAc)_{1 8 0} are studied, and the reaction mechanism is proposed.     

Cyclocondensation of 2-Fluoro-5-nitrobenzaldehyde with Amidines. New Synthesis of Isoquinolines

The direction of the cyclocondensation of 2-fluoro-5-nitrobenzaldehyde with five amidines having -hydrogen atoms has been studied. It was established that depending on the structure of the amidine the main products of the reaction may be not only quinazolines but also 3-aminoisoquinolines. A new convenient route has been found for the synthesis of 3-aminoisoquinolines consisting of the cyclocondensation of -acylacetamidines with 2-fluoro-5-nitrobenzaldehyde.