Crystal structure of the stoichiometric compound Cs2W3O10 with a fractional number of atoms in the unit cell

The crystal structure of Cs₂W₃O₁₀ (a=16.103, c=10.169 Å, $I\bar 4$ , Z=120/11) was determined from three-dimensional X-ray diffraction data (CAD-4 automatic diffractometer, 1612 reflections, R=0.044). The structure has an AB₂O₆ defective pyrochlore motif in which some of the groups consisting of four WO₆ octahedra have been subtracted from the tungsten-oxygen framework and substituted by Cs⁺. The crystal has no vacancies in the substitution site (as confirmed by the occupancy refinement), and the composition of the crystal is strictly stoichiometric with a fractional number of atoms in the unit cell. A similar composition is suggested for the isostructural rubidium compound, which was earlier considered nonstoichiometric.     

Coumarins of three species of the genusHaplophyllum

The results are given of an investigation of three species of the genusHaplophyllum: H. villosum, H. kowalenskyi, andH. tenue, fromwhich five substances of coumarin nature have been isolated. Of them, two substances (I and II) have been identified as scopoletin and lomatin isovalerate, respectively, while suitable structures have been established for the new compounds tenuidin, villosin, and tenudiol. It has been shown that the coumarin composition of the plants changes with the growth site.     

Algorithms for high-level data processing in gas chromatography

Computer processing of gas chromatographic data is discussed, with special emphasis on the numerical operations needed. The CHADIC program is described. This program enables optimal separation conditions to be determined and isothermal gas chromatograms to be processed for qualitative and quantitative analysis.     

Claisen rearrangement taking place in the mass spectrometer

Conclusions The Claisen rearrangement of bucharaine and of the aldehyde bucharainal takes place under the conditions of mass spectrometry. At low temperatures inversion predominates and at high temperatures the anomalous rearrangement.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 577–583, September–October, 1970.     

Volumetric determination of Pt(IV) in the presence of Ir,Pd, and Rh with ferrous ammonium sulfate in alkaline mannitol medium

A potentiometric reductimetric method for the determination of platinum (Pt(IV)Pt(II)) with a standard Fe(II) solution in an alkaline medium of mannitol is described. The method, the error of which does not exceed 2%, can be used in the presence of palladium, iridium, and rhodium.     

Preparation of arylphosphonates by the reaction of aryl halides with tris(trimethylsilyl) phosphite under homogeneous catalysis conditions

The reaction of tris(trimethylsilyl) phosphite with aryl bromides under homogeneous catalysis conditions gives bis(trimethylsilyl)arylphosphonates. The desilylation of these phosphonate products with methanol leads to arylphosphonic acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1461–1462, June, 1991.     

Extraction of macro- and microamounts of lanthanides by D2EHPA

The effect of macroconcentration (Ma) lanthanide extraction on the microcomponent (Mi) extraction by D2EHPA was investigated. The investigation corroborated that the macrocomponent suppresses the microcomponent extraction. The extractability of Mi decreases with increasing Ma concentration and with increasing proton lanthanide number in macroconcentrations. Semi-empirical relations were derived describing lanthanide extraction in lanthanide macro- and microconcentrations as a function of the extraction of lanthanide macroconcentrations. Under the conditions discussed, these relations can be used to estimate for any lanthanide the distribution ratios for the lanthanide applied as a macrocomponent and for Eu applied as a microcomponent.     

Stereoselective synthesis of substituted gamma-butyrolactones by the [3+2] annulation of allylic silanes with chlorosulfonyl isocyanate: enantioselective total synthesis of (+)-blastmycine

[structure: see text]. A stereoselective synthesis of gamma-butyrolactones by the [3 + 2] annulation of allylic silanes with N-chlorosulfonyl isocyanate (CSI) was developed. An enantioselective total synthesis of (+)-blastmycinone was accomplished using this annulation as the key step.     

Tricarbocyanines with dihydropyran,dihydrothiapyran, and N-methyltetrahydropyridine rings in the chromophore

Glutaconic dialdehyde dianil salts, the ,-carbon atoms of which are included in dihydropyran, dihydrothiapyran, or N-methyltetrahydropyridine rings, were synthesized. Tricarbocyanine dyes with epoxydimethylene, epithiodimethylene, or N-methylepiminodimethylene groupings were synthesized by condensation of the dianil salts with a 2-methylbenzothiazole quaternary salt. The color of the dyes is discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 175–178, February, 1976.     

Quantum chemical study of the tautomerism, geometry, and electronic structure of 1,2,3- and 1,2,4-triazoles

A systematic study was carried out on the tautomerism and geometry of 1,2,3- and 1,2,4-triazoles using the semiempirical AM1, PM3, MNDO, and MINDO/3 methods and nonempirical quantum chemical methods taking account of electronic correlation (MP2). The semiempirical methods were found to give incorrect results for the tautomerism of these triazoles, while the nonempirical methods correctly give the energy relationships and show enhanced stability for 2H-1,2,3- and 1H-1,2,4-triazoles attributed to the interaction of the unpaired electron pairs of the adjacent nitrogen atoms. Optimization of the geometry of 2H-1,2,3-triazole by the nonempirical methods showed that bases such as 6-21G and more expanded bases must be used and that electronic correlation should be taken into account. The use of updated calculation methods in the case of 1H-1,2,4-triazole did not give improved results.Prof. Asen Zlatarov University, 8010 Burgas, Bulgaria. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 645–651, May, 1998.