Infrared spectroscopic study of the structure of the tetrabutyl S-dithiopyrophosphate complex of silver

The structure of the complex Ag·TBDTPP (tetrabutyl S-dithiopyrophosphate) formed in HNO₃ medium was studied by IR and NMR methods. The complex is involved in the isomerization of TBDTPP in the presence of Ag⁺ and NO ₃ ⁻ ions. In the IR spectra, we observe the disappearance of P−O−P band and the occurrence of new absorption bands associated with P−S−P and P=O bonds. The silver ion is coordinated to the thiophosphoryl group of the isomer molecule. The influence of HNO₃ concentration on complex formation is discussed.     

Exact spin-pairing energies at the crossovers in octahedral d 4, d 5, d 6, and d 7 transition metal complexes

Exact spin-pairing energies are calculated by direct diagonalization of the relevant ligand field plus interelectronic repulsion matrices for the configurations d ⁴, d ⁵, d ⁶, and d ⁷ of octahedral transition metal ions. The results are presented in terms of /B as function of = C/B for the range of values =3.0 to 8.0. Comparison with the quantity resulting from a simplified approach in which configuration interaction is neglected or considered on an approximate basis only reveals significant differences. Useful estimates of spin-pairing energies are provided, in addition, on the basis of empirical magnetic and electronic spectral data.

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Zusammenfassung Exakte Spinpaarungsenergien für die Konfigurationen d ⁴, d ⁵, d ⁶ und d ⁷ oktaedrischer Übergangsmetallionen werden durch direkte Diagonalisierung der entsprechenden Matrizen des Ligandenfeldes sowie der Elektronenwechselwirkung berechnet. Die Ergebnisse für /B werden in Abhängigkeit von = C/B für den Wertebereich =3.0 bis 8.0 angegeben. Ein Vergleich mit der Größe , die bei einer vereinfachten Behandlung unter Vernachlässigung oder näherungsweiser Berücksichtigung der Konfigurationswechselwirkung erhalten wird, zeigt auffallende Unterschiede. Nützliche Abschätzungen der Spinpaarungsenergie werden außerdem unter Benutzung empirischer magnetischer und elektronenspektroskopischer Daten erhalten.

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Résumé Les énergies exactes de couplage de spin sont calculées par diagonalisation directe du champ de ligand correspondant en plus des matrices de répulsion électronique pour les configurations d ⁴, d ⁵, d ⁶ et d ⁷ des ions octaédriques des métaux de transition. Les résultats sont présentés en termes de /B en fonction de = C/B dan l'intervalle =3,0 à 8,0. On trouve des différences significatives par comparaison de avec les valeurs résultant d'une approche simplifiée sans interaction de configuration ou avec interaction de configuration approchée. De plus, des estimations des énergies de couplage de spin sont obtenues à partir de données empiriques magnétiques et spectrales.

     

Ring closure of some O-aryl ethers of ketoximes to benzofurans

The action of alcohol solutions of hydrogen chloride on aryl ethers of the oximes of N-substituted 4-piperidones (Ia-c) yielded rearrangement products — 3-(2-hydroxyaryl)-4-piperidones (IIa, b) and (or) 4a-aikoxy-l,2,3,4,4a,9b-hexahydrobenzofuro[3,2-c]pyridines (IIIa-c), which, under certain conditions, are readily converted to 1,2,3,4-tetrahydrobenzofuro[3,2-c]pyridines (IVa, b). Ketones of the II type are ketalized to dihydrobenzofurans III by alcohol solutions of hydrogen chloride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1596–1600, December, 1971.     

Austausch von Chrom(III) mit Chrom(II) und Szilard—Chalmers-Reaktion von Kaliumchromat

Zusammenfassung Durch Versuche mit⁵¹Cr wird gezeigt, daß Cr³⁺ mit Cr²⁺ austauscht, wenn man ein Chrom(III)-Salz in wässeriger Cr²⁺-Lösung auflöst, d. h. die Hydratation zum reaktionsträgen [Cr(H₂O)₆]³⁺ verläuft relativ langsam. Die Bedeutung dieses Austausches für dieSzilard—Chalmers-Reaktion von Chromat wird diskutiert.

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Experiments with⁵¹Cr prove the exchange of Cr³⁺ with Cr²⁺ when a Cr(III)-salt is dissolved in an aqueous solution of Cr²⁺. This indicates that the hydration to the inert [Cr(H₂O)₆]³⁺ is relatively slow. The importance of this exchange for theSzilard—Chalmers reaction of chromate is discussed.

     

Platinum(II) Mono-N1-(2"-Tetrahydrofuranyl)-5-Fluorouracilate Complexes with Ammonia

The reaction between cis-[Pt(NH₃)₂Cl₂], N¹-(2"-tetrahydrofuranyl)-5-fluorouracil (HL), and NaOH (taken in a molar ratio of 1 : 1 : 1) or between cis-[Pt(NH₃)₂Cl₂], HL, and Ag₂O (taken in the molar ratio of 1 : 1 : 0.5) was used to synthesize complexes Ia (in the case of NaOH) or Ib (in the case of Ag₂O) with composition Pt(NH₃)₂LCl. The model complex [Pt(NH₃)₃L]NO₃ (II) was synthesized by the reaction between [Pt(NH₃)₃Cl]Cl, HL, AgNO₃, and Ag₂O (1 : 1 : 1 : 0.5). The obtained compounds were characterized by chemical analysis, chromatography, thermogravimetry, conductometry, potentiometry, IR, electronic, and NMR spectroscopies. Complexes Ia and Ib were found to have both similar and different properties. The structures of the compounds and the type of L^– coordination to platinum(II) were suggested. Cytotoxic properties of Iaand Ib were studied.     

Catalytic Titrations of Silver(I) Using an Iodide-Catalyzed Mn(IV)-As(III) Indicator Reaction in the Presence of Sulfuric Acid with Detecting the End-Point by Methods with Two Polarized Electrodes

Catalytic bipotentiometric and biamperometric methods for determining silver(I) with the use of the new manganese(IV)-arsenic(III) indicator reaction catalyzed by iodide ions in the presence of sulfuric acid have been developed. The effects of the sulfuric acid concentration of some ionic species, of the mole ratio of manganese(IV) to arsenic(III) in the solution titrated, and of the titrand temperature, as well as of the current and potential difference, respectively, used for polarization of the indicator electrodes on the conditions for determinations of silver(I) of various concentrations were investigated. The error in the determination of 1.0 g/cm³ silver(I) do not exceed 2%, and the precision of the results is high for both methods.     

Cellular adhesion and proliferation on poly(3,4-ethylenedioxythiophene): Benefits in the electroactivity of the conducting polymer

Cell adhesion and proliferation in poly(3,4-ethylenedioxythiophene), an electroactive polythiophene derivative generated by anodic polymerization, has been investigated. Results show that epithelial cells Hep-2 present significant activity on the surface of poly(3,4-ethylenedioxythiophene) electrodeposited on stainless steel electrodes, no sign of cytotoxicity being detected for this conducting polymer. Indeed, seeded and cultured cells bound better to poly(3,4-ethylenedioxythiophene) than to uncoated stainless steel, the latter substrate being used as a control. Furthermore, the electrochemical characteristics of poly(3,4-ethylenedioxythiophene) covered with cells was determined in different biological media using cyclic voltammetry experiments. Results reveal a significant increase in the electroactivity of this material when it is covered with a cellular monolayer. The overall of the results evidences not only the biocompatibility of poly(3,4-ethylenedioxythiophene) with Hep-2 cells but also their electrocompatibility.     

k0-measurements and related nuclear data compilation for (n, γ) reactor neutron activation analysis

Recommended k₀-factors and related nuclear data for use in (n, γ) activation analysis are given for 72 isotopes. In addition the basic nuclear constants and experimental parameters needed in the k₀ standardization method are reviewed. For convenient data reduction, computer programs were developed.     

Setting the boundary conditions by the potential shift in the self-consistent field (Xα-scattered wave) cluster calculations

Potential shifts given by the Madelung potentials in different regions of a molecular cluster are determined in the MT approximation. Nickel and zinc oxides are employed to consider the interrelation between the approaches to the calculation of the boundary conditions in terms of the Watson sphere and the potential shift in the cluster calculations of perfect and imperfect ionic crystals using the self-consistent field (Xα-scattered wave) method. Translated fromZhurnal Strukturnoi Khimii, Vol. 38, No. 1, pp. 23–31, January–February, 1997. Original article submitted February 12, 1996.