The preparation,phase relationships,and Eu-151 Mössbauer spectroscopy of europium tungsten bronzes and related phases

Crystal chemistry and phase relations for the bronze-forming region of the EuWO system have been investigated. A bronze Eu_xWO₃ is stable up to 1000°C when x ? 0.125 and in the region 0.085 ? x ? 0.125 the symmetry is cubic. A tetragonal bronze exists at x = 0.05, and an orthorhombic bronze with a structure closely related to the orthorhombic form of WO₃ exists below x = 0.01. Mössbauer spectra at room temperature and at 80 K indicate that in all these phases the europium is highly ionized as Eu(III) with no electron localization to give (EuII) even at low values for x. The decomposition products of the bronzes have been established, and the Mössbauer parameters for the highly nonstoichiometric tungstates Eu_xWO₄ were determined. Both Eu(II) and Eu(III) resonances were obtained, and a cation vacancy model for Eu_xWO₄ was found to fit the data best. In conformity with the foregoing data, a sample of composition “Eu₂W₂O₇” was found not be be a pyrochlore but to comprise a mixture of Eu₆WO₁₂, Eu_xWO₄, and W. The phase relationships for the europium bronze system Eu_xWO₃ are compared with those of other ionic bronzes Na_xWO₃, Li_xWO₃, and Al_xWO₃.     

Thermal addition of dibenzoylacetylene to cycloheptatriene and the photo-rearrangement of the thermal adduct

The reaction of cycloheptatriene (CHT) with dibenzoylacetylene (DBA), in refluxing toluene gave a mixture of products consisting of 6,7-dibenzoyltricyclo[3.2.2.0^2.4]nona-6,8-diene 6 and 3,4-dibenzoylbicyclo [3.2.2]nona-2,6,8-triene 7. Neat heating of a mixture of CHT and DBA around 95–100° gave besides, 6 and 7, small amounts of two dimers of DBA. Photolysis of 6 in benzene solution gave a lactonic, rearrangement product. 25. The structures of the various products have been established and reasonable mechanisms for their formation have been suggested.     

Lanthanon (III) Complexes of Bifunctional Tridentate and Tetradentate Schiff Bases

Reactions of isopropoxides of praseodymium, neodymium and samarium with bifunctional tridentate and tetradentate schiff bases (i.e. salicylidene-O-aminophenol and bis-salicylaldehyde ethylenediamine) have been carried out in benzene in different stoichiometric ratios resulting in the formation of products with the formula M(OPrⁱ)(C₁₁H₉NO₂), M(C₁₃H₉NO₂)(C₁₃H₁₀NO₂). M₂(C₁₃H₉NO₂) M(OPrⁱ)(C₁₅H₁₄N₂O₂), M(C₁₆H₁₄N₂O₂)(C₁₆H₁₅N₂O₂) and M₂(C₁₆H₁₄N₂O₂)₃ (where M stands for Pr, Nd and Sm). The products were found to be yellow to orange solids soluble in benzene and alcohol. The absorption spectra of these complexes were also recorded in methanol.     

Thiapyrylium salts (review)

The literature data touching upon the synthesis of thiapyrylium salts and the stability of the thiapyrylium cation as compared with its isoelectronic analogs, as well as the nucleophilic, oxidation, anion-exchange, and other reactions of the salts with substituted and unsubstituted thiapyrylium cations are examined in this review.     

Reaction of mercury(II) and xylenol orange-I Effect of the buffering media

The influence of the buffering medium on the reaction of Hg(II) with Xylenol Orange has been studied. Amine-type compounds are complexed by Hg(II)/Xylenol Orange with a sharp hyperchromic effect on the reagent itself, at 590 nm, but complex formation of Hg(II)/Xylenol Orange in non-amine-type buffer, such as citric acid-phosphate, gives a hypochromic effect on Xylenol Orange at 580 nm. Hg(II) is determined at pH 7.5 in two ranges of concentration, 2-9 ppm in citrate buffer, measured at 580 nm ( = 2.50 x 10(4)), and 6-11 ppm in hexamine buffer, at 590 nm ( = 4.18 x 10(4)).     

Influence of mobility of medium on dynamics of metallotropy in tin-containing 2-R-oxyphenoxyls

The rate of intramolecular migration of the triphenylstannyl group in 3,6-ditert-butyl-2(triphenylstannyl) oxyphenoxyl decreases with increasing viscosity of the medium. A linear relationship _ex=·_c is observed between the characteristic time of stannotropy _ex and the correlation time for reorientational motions of the radical _c within a range of temperature variation no greater than 30°C. The parameter depends on the medium; this is explained by the possibility of complexation of the radical with the solvent.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 781–786, April, 1990.     

Hulthén and slater type 2d functions in some excited configurations of sulphur and phosphorus

It is shown that a substantial energy improvement is gained by the variational use of Hulthén orbitals, instead of single Slater orbitals, in the 3d shells of some excited configurations of sulphur and phosphorus. The energies obtained are close to those attained with two-term Slater functions. In some cases the radial distribution functions from Hulthén orbitals are as good an approximation of SCF radial distributions as those from two-term Slater orbitals. Single term 2d functions with only one parameter are found to give almost identical energies and radial distribution functions as those obtained from two-parameter Hulthén orbitals. It is shown that the relationship between one-term 2d orbitals and Hulthén orbitals gives a method of enforcing nuclear cusp conditions on the former with little effect on the energy.     

Separation of alkylaminonaphthylenesulfonyl peptides and amin acids by high-performance liquid chromatography. Methods for measuring melanotropin inhibiting factor breakdown

N,N-Dimethyl diethyl, dipropyl, dibutyl, and N-monoisopropylaminoaphthylenesulfonyl derivatives of melanotropin inhibiting factor (MIF) and its metabolites were prepared, and their chromatographic behavior was investigated with thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), using five solvent systems on polyamide layers and ten solvent systems on muBondapak C18 and muBondapak phenyl columns. A mixture of MIF and its metabolites derivatized with Dns chloride was adequately resolved by two-dimensional chromatography on polyamide layer with solvent systems, formic acid-water (3:97) and benzene-acetic acid (9:1). Bns-MIF and its metabolites were separated with muBondapak C18 column with the solvent system acetonitrile-0.01 M sodium sulphate buffer, pH 7 (50:50). They were separated into five groups: Gly and Bns acid; Pro-Leu, Leu-Gly and Leu; Pro; Gly-NH2; and MIF. The alkylaminonaphthylenesulfonyl derivates had strong fluorescence, which permitted their detection at the level of 10(-11) to 10(-9) mol. Dns-MIF and its derivatives had the lowest detectable amounts. HPLC with the aid of the Dns derivation is reliable and fast, and is the preferable method for study of neuropeptide breakdown.     

Research in the isoxazole series

The 4-nitro derivative is formed in the nitration of 3,5-diphenylisoxazole (I) in acetic anhydride. Mononitration of isoxazole I in concentrated H₂SO₄ gave 3-phenyl-5-(p-nitrophenyl)isoxazole, while polynitration gave a mixture of dinitro derivatives, among which 3- (m-nitro-phenyl)-5-(p-nitrophenyl)isoxazole was identified. The structures of the isolated products were established by means of the spectra, by reaction-chromatography methods, and gasliquid chromatography, as well as by a comparison with genuine samples of the two mononitro and four dinitro derivatives of isoxazole I.