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61.
A density functional study of exchange coupling was carried out for a series of heterobinuclear oximato-bridged transition metal complexes. Model calculations were used to examine the influence of the electronic configuration of the metal atoms on the coupling constants. This analysis was complemented by a study of the variation of the coupling constant with the most usual structural distortions within this family of compounds. The influence of the nature of the terminal ligands as well as that of the symmetry on the bridge were also investigated.  相似文献   
62.
Zusammenfassung 42 Heterocyclen, die sich formal von alternierenden und nichtalternierenden Kohlenwasserstoffen durch Ersatz einer Doppelbindung durch die Heteroatome Sauerstoff, Stickstoff, Schwefel und Selen ableiten, werden nach dem Pariser-Parr-Pople-Verfahren berechnet und ihre Spektren im nahen Ultraviolett und Sichtbaren beschrieben. Schwefel und Selen werden dabei im LCAO-MO-Verfahren nach dem p-Modell behandelt. In den meisten Fällen können die Berechnungen nicht nur die spektralen Charakteristika gut wiedergeben, sondern auch Beziehungen in den Spektren iso--elektronischer Verbindungen gleicher Struktur verständlich machen. Berechnungen an kationischen Stickstoffheterocyclen führten dann zu falschen Ergebnissen, wenn die Stickstoffparameter vom Pyrroltyp übernommen werden.
PPP-calculations and comparison of electronic spectra of iso--electronic oxygen, nitrogen, sulfur, and selenium heterocycles
42 heterocyclic compounds, formally derived from alternant or nonalternant hydrocarbons by replacing a C=C group by an oxygen, nitrogen, sulfur or selenium atom, are studied by the Pariser-Parr-Pople-type of calculation. By means of these results the near ultraviolet and visible spectra are described. The sulfur and the selenium atoms are treated in the LCAO-MO-method using the p-model. In most cases spectral features are not only well reproduced, but interrelations of the spectra of iso--electronic compounds, possessing analogous structures are interpreted, too. On calculating cationic nitrogen heterocycles using parameters of pyrrol type nitrogen results are unsatisfactory.

Résumé 42 composés hétérocycliques, formellement dérivés d'hydrocarbures alternants ou non alternants par remplacement d'un groupement C=C par un atome d'oxygène, d'azote, de soufre ou de sélénium, sont étudiés par la méthode de Pariser-Parr-Pople. Les résultats obtenus permettent de décrire le spectre U.V. proche et visible. Soufre et sélénium sont traités en utilisant le modèle p. Dans la plupart des cas les caractères spectraux sont non seulement correctement reproduits, mais les relations entre les spectres des composés iso--électroniques à structures analogues peuvent être interprétées. Les calculs concernant les heterocycles à azote cationique sont insatisfaisants lorsqu'ils sont effectués avec des paramètres de l'azote du type pyrrole.


Anmerkung: Die Arbeit wurde in dem von Prof. Dr. R. Mayer geleiteten Schwefelarbeitskreis der TU Dresden durchgeführt.  相似文献   
63.
64.
Zusammenfassung Der Einfluß von Atmosphäre, Aufheizungsgeschwindigkeit und Spülgasgeschwindigkeit auf die thermische Zersetzung von Alkalibenzolsulfonaten wurde untersucht. Kristallwassergehalt, Dehydratations-temperatur und -wärme, gegebenenfalls die Zusammensetzung, Art, Temperatur und Wärme der Modifikationsänderungen, Schmelzpunkte und Schmelzwärmen der Verbindungen wurden bestimmt. Die Zersetzung verläuft in zwei Abschnitten. In dem ersten Hauptteil entstehen in Inertgasatmosphäre Diphenyloxid, Diphenyl, Diphenylsulfon, Benzol, Phenol, Thiophenol, Diphenylsulfid, Thiantren, Diphenylenoxid und wahrscheinlich Diphenylensulfid, weiterhin Koks, Schwefeldioxid, Natriumsulfit und wenig Natriumsulfat, Natriumsulfid, Acetylen und Wasser. Im zweiten Hauptzersetzungsvorgang entstehen Natriumsulfid und Kohlenoxid. Die Produkte wurden isoliert und analysiert. Dazu wurden Derivatographie, Differentialthermoanalyse, Gaschromatographie, Infrarotspektroskopie, kontinuierliche thermische Titration und chemische Methoden gemeinsam angewandt.
Summary An investigation was made of the influence of the atmosphere, rate of temperature rise, and velocity of the purging gas on the thermal decomposition of alkali benzene sulfonates. The crystal water content, the dehydration temperature and heat, and if need be the composition, the kind, temperature, and heat of the modification changes, melting points and heats of fusion of the compounds, were determined. The decomposition proceeds in two stages. In the first main stage (in an inert atmosphere) the resulting compounds include diphenyl oxide, diphenyl, diphenylsulfone, benzene, phenol, thiophenol, diphenyl sulfide, thianthrene, diphenylene oxide and probably diphenylene sulfide; also coke, sulfur dioxide, sodium sulfite and a little sodium sulfate, sodium sulfide, acetylene, water. Sodium sulfide and carbon monoxide are formed in the second main decomposition. The products were isolated and analyzed. Furthermore, use was made of derivatography, differential thermal analysis, gas chromatography, infra red spectroscopy, continuous thermal titration, and chemical methods.

Résumé On a étudié l'influence de l'atmosphère, de la vitesse d'échauffement et de balayage du gaz, sur la décomposition thermique des benzène-sulfonates alcalins. On a déterminé la teneur en eau de cristallisation, la température et la chaleur de déshydratation, éventuellement la composition, la nature, la température et la chaleur des changements d'état, les points de fusion et les chaleurs de fusion des composés. La décomposition s'effectue en deux temps. Tout d'abord, en atmosphère inerte, il se forme de l'oxyde de diphényle, du diphényle, de la diphénylsulfone, du benzène, du phénol, du thiophénol, du sulfure de diphényle, du thianthrène, de l'oxyde de diphénylène et probablement du sulfure de diphénylène, et aussi du coke, de l'anhydride sulfureux, du sulfite de sodium et, en moins grande quantité, du sulfate de sodium, du sulfure de sodium, de l'acétylène et de l'eau. Dans une deuxième étape de la décomposition principale, du sulfure de sodium et de l'oxyde de carbone prennent naissance. On a isolé et analysé ces produits. Pour cela, on a utilisé simultanément la dérivatographie, l'analyse thermique différentielle, la chromatographie en phase gazeuse, la spectroscopie infrarouge, le titrage thermique en continu et les méthodes chimiques.


Vorgetragen beim Symposium für analytische Chemie in Graz, 29. September bis 1. Oktober 1965.  相似文献   
65.
Summary When measuringQ –1 and the flexural resonance frequency of bars clamped at one end, constituted by a viscoelastic polymeric material glued to a rigid support of modulusE 1, it is possible to calculate the componentsE 2 andE 2 of the complex elastic modulus of the polymeric material examined. In this work the minimum (critical) value of the ratioa=E 2 /E 1=a c and the values of the ratioQ 2 –1/Q –1=F 1 are evaluated beyond which no exact calculation ofE 2 and ofQ 2 –1 is possible.Within the confidence limits of the linear viscoelasticity theory, these values depend on the accuracy of measurement of both frequency and resonance curve, as well as on the instrument employed, on the operating temperature and on the ratio between the thicknesses of the two coupled materials.In order to keep outside the critical conditions, the most convenient method involves the use of measurements of coupled test-pieces having different ratiosz between their thicknesses and of supports having different modulusE 1, depending on the field of temperature of the analysis ofE 2 and tg 2 concerning and E.P.R. elastomer and a vulcanized cis-1,4 polyisoprene in very wide ranges of temperature comprising the glass transition. Moreover, it is demonstrated by analysis the shift on the temperature axis of the tg maximum of the composite test-piece with respect to the position of the tg maximum of the polymeric material alone.With 11 figures and 1 table  相似文献   
66.
Colloid and Polymer Science - Data on the surface tension of sodium alkylsulfonate solutions at different temperatures and surfactant concentrations are presented. By applying the thermodynamic...  相似文献   
67.
68.
Dependence of two-photon absorption (TPA) rate on the state of polarization of a laser beam is investigated in the low-temperature orthorhombic modification of Hg2Cl2 crystals. Theoretical calculations of the dependence of TPA rate on the direction of polarization vector of the beam are performed for centrosymmetric points, Y, Z, T, R andS of the Brillouin zone. The domain structure of real crystals is taken into consideration and it is shown that periodicity of the polarization dependence may indicate whether TPA is due to transitions either at, Y, Z, T orR, S points. The polarization dependence of TPA cannot, however, distinguish between points inside these two groups. Comparison of theory with a low-temperature (T 8·5 K) experimental curve of polarization dependence is discussed. It is shown that the experiment can be explained in main features by a model of noninteracting oriented linear dipoles. Further, on the basis of TPA measurements, a simple energy band structure of Hg2Cl2 is proposed regarding Hg2Cl2 crystal as a linear chain of molecules.The authors express thanks to Dr. . Barta for supplying the Hg2Cl2 crystals, Dr. Z. Bryknar for critical comments and Dr. B. Velický for stimulating discussion. We thank also Dr. V. Kohlová for assistance during measurement.  相似文献   
69.
A simple model including different processes important for the creation of APS signals formed by electrons is proposed. Mean probabilities of elastic and inelastic interactions of electrons with individual atom layers in the solid are introduced. The contribution of different layers to the DAPS and AEPS signals and the dependence of these signals on the interaction parameters are calculated.I am indebted to dr. J. Pavluch for valuable discussions.  相似文献   
70.
The paper describes the results of investigations of the solar wind ions, carried out on board the high apogee Prognoz 7 and Prognoz 8 Earth's satellites with the aid of an SKS instrument (USSR) and a Monitor instrument (USSR-SSR). Behaviour of proton and that of components on the front of Earth's bow and interplanetary shock waves were compared by means of the energoanalysis and energy-mass analysis techniques. In several long-term periods of observation the solar wind heavy ions — oxygen, silicon and iron were determined. It enabled us to estimate the solar corona chemical composition and electron temperature.Presented at the 5th General Assembly IAGA/IAMAP August 5–17, 1985, Prague, Czechoslovakia.  相似文献   
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