Die Bestimmung von Sauerstoff in metallischem Natrium

Ohne Zusammenfassung     

MO-LCAO-Berechnungen an schwefelhaltigen π-Elektronensystemen

Zusammenfassung Mercaptobenzol wird als ein 8-Elektronensystem mit sieben Basisorbitalen nach einem SCF-CI-Verfahren in Pariser-Parr-Pople-NÄherung behandelt. Alle Einzentrenabsto\ungsintegrale werden gleichgesetzt ( _CC=_SS=10,84 eV) und die Zweizentrenabsto\ungsintegrale nach der Mataga-Nishimoto-Beziehung ermittelt. An Hand des UV-Absorptionsspektrums von Mercaptobenzol zwischen 155 und 300 m werden für U _S=21 eV und _CS=0,5 _CC empirisch abgeleitet. Die Berechnungen an Mercapto- und Methylmercaptobenzol erlauben neben einer Interpretation der UV-Spektren Aussagen über Ionisationseigenschaften und die Ladungsverteilungen, die in guter übereinstimmung mit dem Experiment stehen. Die Brauchbarkeit der vorgeschlagenen Parameter wird durch Berechnungen an 1,2-, 1,3- und 1,4-Dimercaptobenzol, 1- und 2-Mercaptonaphthalin und 9-Mercaptoanthracen nachgewiesen.

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Mercaptobenzene is treated as an 8-electron-system with seven basis orbitals according to an SCE-CI-method in the Pariser-Parr-Pople approximation. All of the one-center repulsion integrals were assumed to be the same ( _CC=_SS=10.84 eV) and the two-center repulsion integrals were determined according to the Mataga-Nishimoto-relation. Values of U _s =21 eV and _CS=0.5 _CC were derived empirically from the UV-absorption spectrum of mercaptobenzene in the region 155–300 m. The calculations on mercapto- and methylmercaptobenzene, besides allowing an interpretation of the UV-spectra, give predictions of ionization properties and charge distributions showing good agreement with experiment. The usefulness of the suggested parameters is shown with calculations on 1,2-, 1,3- and 1,4-dimercaptobenzene, 1- and 2-mercaptonaphthalene and 9-mercaptoanthracene.

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Résumé Mercaptobenzène est traité comme un système de 8 électrons avec sept orbitales de base dans une méthode SCF-CI en approximation PPP. Les valeurs de U _S=21 eV et _CS=0,5 _CC sont obtenues à l'aide du spectre d'absorption U.V. Les calculs en Mercapto- et Méthylmercaptobenzene permettent aussi bien une interprétation des spectres U.V. comme des indications sur la ionisation et la distrubation de charge qui sont en bonne relation avec les experimentaux. Avec les paramètres proposés en recoit aussi pour 1,2,1,3-, 1,4- Dimercaptobenzène, 1- et 2-Mercaptonaphtaline et Mercaptoanthracène des résultats valables.

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X. Mitteilung: Fabian, J.: Wiss. Z. Techn. Univ. Dresden 1967. (Im Druck.)

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Herrn Dr. R. Zahradník (SAV Prag), der diese Arbeit ma\geblich gefördert hat, danken wir für die Durchsicht des Manuskriptes. Für die überlassung der Dimercaptobenzole sind wir Herrn Dr. J. Morgenstern (TU Dresden) sehr verbunden.     

Die Trennung von C6F14-Isomeren durch Gaschromatographie

Ohne Zusammenfassung     

Synthesis and Crystal Structure of Na7Cu3O8, Containing a New Type of Oxocuprate(III) Oligoanion

Na₇Cu₃O₈ was prepared through oxidation of a Na₃CuO₂/NaCuO mixture (2:1) in dried oxygen at 450 °C. Single crystals have been grown by annealing of Na₇Cu₃O₈, in the presence of Na₂O₂, at 450 °C for 2000 h in silver crucibles, which were sealed in glass ampoules under dried Ar. According to the X-ray analysis of the crystal structure ( , Z = 1, a = 5.5891(2), b = 6.0945(2), c = 7.8890(3) Å, α = 110.059(2), β = 108.669(2), γ = 90.237(2)°) a new Cu₃O₈^7- oxocuprate anion, consisting of three edge sharing CuO₄ squares, is the prominent structural feature. These anions are aligned parallel to the space diagonal of the unit cell and can be regarded as infinite chains from which every fourth copper atom has been removed. This new representative of an oxocuprate(III) anion gives support to the expectation that the gap between dimeric and infinite edge sharing units of square planar cuprate anions can be closed, in principle.     

Structure-acidity-IR spectra correlations for p-substituted N-phenylsulfonylbenzamides

The wavenumbers of the IR absorption bands of the C=O, S=O and N-H stretching vibrations for a series of p-substituted N-phenylsulfonylbenzamides were measured in trichloromethane. The bond orders, Mulliken charges, charge densities and heats of formation were calculated using the PM3 method. Fifty significant mutual mono parameter (MP) and six dual parameter (DP) correlations were found for the IR spectral, theoretical structural data, substituent constants and previously reported dissociation constants in five polar organic solvents. The transmission of the substituent effects has been discussed and the solvent effect on the slopes of some linear correlations was evaluated using different solvent parameters. The results showed that the factors describing the electronic structure and controlling the dissociation equilibrium and the IR spectra properties of p-substituted N-phenylsulfonylbenzamides must be the same.     

Total syntheses of (+)-cylindricines C-E and (-)-lepadiformine through a common intermediate derived from an aza-Prins cyclization and Wharton's rearrangement

[reaction: see text] Enantioselective total syntheses of (+)-cylindricines C-E and (-)-lepadiformine through a common tricyclic intermediate are described here. These syntheses are concise and feature an aza-Prins cyclization and a seldom-used Wharton rearrangement en route to the common intermediate.