Simultaneous vibrational relaxation and thermal dissociation of diatomic molecules

A model of a truncated harmonic oscillator with equidistant levels and one-quantum transitions is applied. The balance equations for O₂ have been solved numerically with 26 levels, with the transition probabilities taken as P _k,k +1k exp (k) P ₁₀, in which k is the number of the level and is an adjustable parameter that takes account of the anharmonicity. A Boltzmann distribution is obtained up to level 19 with =0, but for 0 there are deviations from that distribution in lower levels. Levels with k=1, 2, 3 are populated with relaxation times substantially less than the relaxation time for the vibrational energy. Dissociation depletes levels with k 19.     

Dynamic shear modulus in the splitting region of poly(alkyl methacrylates)

A systematic study of the dynamic shear modulusG ^*=G+G in three poly(alkyl methacrylates) (PEMA, PnPMA, PnBMA) at frequencies between 0.001 and 500 rad/s is presented. As the splitting frequencies _s are low, aging effects can be observed in the splitting region. There is a systematic shift of the splitting frequency _s to lower values with increasing length of the alkyl side group. In PnBMA a separate shear appearance is observed about two frequency decades below the local mode . This is discussed in terms of the concept of minimal cooperativity. Aging effects are: Shift of the maximum loss frequency to lower values, peak sharpening of the relaxation, and intensity changes of and . These effects are discussed in terms of the sequential aging concept. Aging leads to a pronounced bending of the traces upwards from the equilibrium line in the Arrhenius diagram. These non-equilibrium phenomena are promoted by the small slope m=d(log )/dT of the trace in the splitting region.Dedicated to Prof. E. W. Fischer at the occasion of his 65th Birthday Lieber Herr Fischer, die Hallenser Polymerphysiker danken Ihnen aufrichtig für die warmherzige und effektive Förderung der Polymerwissenschaften im Raum Halle-Merseburg.     

Crystal and molecular structure of trans-diiodobis-(1-methyl-5-nitroimidazole)platinum(II)

Summary A new platinum complex of 1-methyl-5-nitroimidazole has been obtained and characterized by elemental analysis, i.r. and n.m.r. spectroscopy. The structure of [PtI₂-(C₄ H₅N₃O₂)₂] has been determined by single-crystal X-ray diffraction. The crystals are triclinic: P1, a = 15.640(3), b = 12.617(2), c = 6.701(1) , = 102.77(5), = 101.15(5), = 100.71(5)°, V = 1228.6(3) ³, Z = 3, D_x = 2.851(6) Mg m^–3, (MoK ) = 0.71069 , = 12.85 mm^–, F(000) = 948, final R = 0.038 for 2859 reflections. The complex consists of monomeric PtI₂(1-methyl-5-nitroimidazole)₂ units. The coordination geometry is square-planar. The two 1-methyl-5-nitroimidazole ligands are trans coordinated to platinum.     

Deutung der K α-satelliten bei leichten Elementen

Zusammenfassung Ausgehend von der KL-Ionisation wurden die K -Satelliten(, , ₃, ₃, ₄) der Elemente Z=8 bis Z=12 den entsprechenden Übergängen zugeordnet. Die Berechnung der Übergänge wurde nach der Z-Dependence-Theorie bis einschließlich zweiter Näherung durchgeführt.

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Interpretation of the K -satellites of the light elements

Starting from the KL-ionisation the K -satellites(, , ₃, ₃, ₄) of the elements Z=8 to Z=12 have been assigned to the corresponding transitions. The transitions have been calculated by the Z-dependence-theory including the second approximation.

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Résumé Les satellites K (, , ₃,₃, ₄) des éléments Z= 8 à Z=12 ont été attribués aux transitions correspondantes à partir de l'ionisation KL. Les transitions ont été calculées par la théorie dépendant de Z en tenant compte de l'approximation seconde.

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Herrn Prof. Timm in dankbarer Würdigung der Hilfen, die die BASF für den Aufbau unserer theoretisch-chemischen Arbeitsgruppe geleistet hat, zum 60. Geburtstag gewidmet.

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Der Deutschen Forschungsgemeinschaft dankt D. H. für die finanzielle Unterstützung, die die Dunchführung dieser Arbeit wesentlich erleichterte.     

Solubility Study of Nimodipine Inclusion Complexation with α- and β-Cyclodextrin and some Substituted Cyclodextrins

The solubility of nimodipine was measured in aqueous solutions of the following cyclodextrins: -cyclodextrin (-CD), hydroxypropyl--CD (HP--CD), -cyclodextrin (-CD), random substituted methyl--CD (M--CD), three hydroxypropyl--CDs (HP--CD) with mutually different average degree of substitution, and hydroxypropyl--cyclodextrin (HP--CD). From the determined linear solubility diagrams the values of the binding constant K₁₁ of the inclusion complexes of nimodipine with the respective CDs were evaluated. The -CDs efficiently solubilized sparingly soluble nimodipine, the highest value of K₁₁ was found for M--CD (1680 M^-1), followed by -CD (550 M^-1) and HP--CDs, where the higher degree of substitution lowered K₁₁. Only slight solubilization of nimodipine was observed in the solutions of the -CDs and HP--CD.     

Zusammenhang zwischen den K α-Satelliten-Linien und den Röntgenübergängen vom Typ K 1 L 1→L 2 bei den Elementen Neon,Natrium, Magnesium,Aluminium und Silizium

Zusammenfassung Für die Elemente Neon, Natrium, Magnesium, Aluminium und Silizium werden mit einem quantenmechanischen Variationsverfahren unter Verwendung einer minimalen STF-Funktionenbasis Röntgenübergänge vom Typ K ¹L¹L² berechnet und den K -Satellit-Linien , , ₃, ₃ and ₄ zugeordnet.

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Relation between K -Satellits and X-ray-transitions of the type K ¹ L ¹L ² for Ne, Na, Mg, Al and Si

STF-Calculations are reported for X-ray-transitions of the type K ¹L¹L² for Ne, Na, Mg, Al and Si. It is shown that these transitions are correlated with the K -satellits , , ₃, ₃ and ₄.

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Die Wellenfunktionen können auf Anfrage zur Verfügung gestellt werden.     

Transformed steroids

Conclusions The addition of thioacetic acid to the ⁵ bonds of 16- and 16-mercapto-3-hydroxypregn-5-en-20-one 3,16-diacetates (II) and (III) under radical conditions gives not only trans-diaxial addition products-6,16- and 6,16-dimercapto-3-hydroxy-5o;-pregnan-20-one 3,6,16-triacetates (IV) and (V) -but also cis-addition products-6,16- and 6,16-dimercapto-3-hydroxy-5-pregnan-20-one 3,6,16-triacetates (VI) and (VII).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 405–411, February, 1969.     

Crystal Structures of [Ni(Phen)(i‐Bu2PS2)2] and [Ni(Phen)3](i‐Bu2PS2)2 Complexes and Interaction between Coordinated 1,10‐Phenanthroline Molecules

Single crystals of [Ni(Phen)(iBu₂PS₂)₂] (I) and [Ni(Phen)₃](iBu₂PS₂)₂ (III) compounds were grown, and their structures were determined by Xray diffraction analysis (CAD4 diffractometer, MoK radiation, 3336 F _hkl , R = 0.0373 for I and 2575 F _hkl for III). The crystals of complex I have a triclinic unit cell with the following parameters: a = 11.097(1) , b = 14.903(2) , c = 22.650(3); = 75.18(1)°, = 80.50(1)°, = 75.07(1)°, V = 3479.2(7)³, Z = 4, _calc = 1.255 g/cm³, and space group 1; the crystals of III have a monoclinic unit cell with the following parameters: a = 19.010(3), b = 15.481(1) , c = 17.940(3); = 97.58(1)°, V = 5233.5(12)³, Z = 4, _calc = 1.292 g/cm³, and space group C2/c. The structure of complex I is built from mononuclear molecules, and the structure of III, from [Ni(Phen)₃]²⁺ complex cations and i Bu₂PS₂ ^- outersphere anions. The NiN₂S₄ coordination polyhedra in the structure of I and NiN₆ in the structure of III are distorted octahedra. Based on structural data, the interaction between the coordinated Phen molecules of complexes I, [Ni(Phen)₂(iBu₂PS₂)](iBu₂PS₂) (II), and III is considered, as well as the packing modes of these complexes.     

Simultaneous determination of environmental α-radionuclides using liquid scintillation counting combined with time interval analysis (TIA) and pulse shape discrimination (PSD)

Some improvements of the detection sensitivity in pulse time interval analysis (TIA) based on selective extraction of successively - correlated decay events within millisecond order from random or background events, were established by the utilization of PSD, to reject /-pulses from -ones and a simple chemical procedure of radium separation, together with the use of well resolved scintillator. By applying the PSD, the contribution of -decay events was completely eliminated in both the -spectra and the TIA distribution curves as well as the improvement into clear energy resolution and the enhancement of detection sensitivity for the TIA. As a result, the TIA and -spectrometric analysis of²²⁶Ra-extract showed the existence of²²³Ra (Ac-series) and /-correlated events with correlated life (due to 0.16 ms due to²¹⁴Bi()²¹⁴Po()) along with a singly well resolved -peak to be useful for the determination of²²⁶Ra (U-series). The difference of half-lives (145 and 1.78 ms) due to²¹⁶Po and²¹⁵Po (direct daughters of²²⁴Ra for Th-series and²²³Ra for Ac-series, respectively) was also proven for the possibility of the simultaneous determination of both correlated events by using the TIA/PSD combined with chemical separation and liquid scintillation counting method. Finally, the simultaneous determination of three natural decay series, which include U-, Th- and Ac-series nuclides, have been conveniently carried out for some environmental samples using the present method combined with²²⁵Ra yield tracer (Np-series).     

Eigenvalues of the real generalized eigenvalue equation perturbed by a low-rank perturbation

The low-rank perturbation (LRP) method solves the perturbed eigenvalue equation (B +V) _k = _k (C +P) _k , where the eigenvalues and the eigenstates of the related unperturbed eigenvalue equationB _i = _i C _i are known. The method is designed for arbitraryn-by-n matricesB, V, C, andP, with the only restriction that the eigenstates _i of the unperturbed equation should form a complete set. We consider here a real LRP problem where all matrices are Hermitian, and where in addition matricesC and (C +P) are positive definite. These conditions guarantee reality of the eigenvalues _k and _i . In the original formulation of the LRP method, each eigenvalue _k is obtained iteratively, starting from some approximate eigenvalue _k . If this approximate eigenvalue is not well chosen, the iteration may sometimes diverge. It is shown that in the case of a real LRP problem, this danger can be completely eliminated. If the rank of the generalized perturbation {V, P} is small with respect ton, then one can easily bracket and hence locate to any desirable accuracy the eigenvalues _k (k = 1, ...,n) of the perturbed equation. The calculation of alln eigenvalues requiresO(² n ²) operations. In addition, if the perturbation (V, P) is local with the localizabilityl p, then onlyO(² n) operations are required for a derivation of a single eigenvalue.     

Electroconductivity and Ion Transport in Protonic Solid Electrolytes BaCe0.85R0.15O3–δ, where R is a Rare-Earth Element

The total, ionic, and protonic conductivities of solid electrolytes BaCe_0.85R_0.15O_{3 –} (BC15R), where R = Sc, Y, La, and all lanthanides bar Pm, are studied at ₂ = 2.1 × 10⁴–10^–15 Pa, ₂ = 2.1 × 10³ Pa, and temperatures of 550–1000°. The samples are synthesized in air at 1450° for two hours. In oxidizing media, all the electrolytes are mixed ion–hole conductors. In reducing environment, BC15R doped with R³⁺ exhibit oxygen–proton conduction. Ionic and protonic conductivities are independent of ₂. Protonic conductivity disobeys the Arrhenius dependence: it decreases with increasing temperature. The total and ionic conductivities of BC15R are virtually independent of the nature of cations R³⁺ in the interval from Nd to Lu.     

Solvent/water partitioning of dimethylmethylphosphonate (DMMP) as a probe of solvent acidity

Experimentally determined partition coefficients for DMMP between NaCl-saturated water and 20 solvents were correlated using the solvatochromic parameters , , and ^*. An inverted LSER was then used to predict for 7 additional solvents. The new cohesion parameters and ^*2 were found to be more representative of cavity formation than _H ² . Most importantly, it was essential to include either or _H ² in the LSER. The partition method appears to be a useful adjunct to solvatochromic techniques in refining and extending the scale of solvent acidity and could be used to rationalize solvent selection in extraction processes.     

Regioselective synthesis of α- and α'-sulfur-containing ethyl esters of dehydrodesthiobiotin

Conclusions The ethyl esters of- and'-oxodehydrodesthiobiotin when reacted with thioacetic acid in the presence of BF₃ etherate respectively give the ethyl esters of-thiooxo- and, -diacetytmercaptodehydrodesthiobiotin.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 954–956, April, 1978.     

Comparative study of the catalytic properties of V2O5, Nb2O5 and Ta2O5 in the oxidation of methanol to formaldehyde

The selectivity of the oxides under consideration to the oxidation of methanol to formaldehyde is shown to increase in the sequence V₂O₅–Nb₂O₅–Ta₂O₅. The same sequence corresponds to the decrease in specific activity. The activation energy of the reaction is 12 kcal/mol for V₂O₅, 14 kcal/mol for Nb₂O₅ and 22 kcal/mol for Ta₂O₅.

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, V₂O₅–Nb₂O₅–Ta₂O₅. . : V₂O₅ 12 /, Nb₂O₅ 14 / Ta₂O₅ 22 /.

     

Complex polarizability as used to analyze dielectric relaxation measurements

The effect of representing dielectric properties in terms of the complex polarizability ^c = – i is examined. Loss curves ( and tan ) are shifted towards higher frequencies, revealing the existence of new relaxations and allowing the clarifications of ones already known. We have calculated the shift ratios (at maximum or tan )/ (at maximum or tan ) from the more conventional empirical equations representing the dielectric behavior. Some examples are given.     

On theC v toC p conversion for solid linear macromolecules

TheC _v toC _p conversion for solid linear macromolecules via the Nernst-Lindemann equationC _p -C _v =A ₀,C _p ² T/T_m is discussed on hand of data for 10 crystals and seven glasses. An average value ofA ₀=(5.11±2.41) · 10^–3 mol K J^–1 was calculated if the mole is assumed to refer to heavy atoms only. ThisA ₀ is numerically equal to the original Nernst—Lindemann constant.

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Zusammenfassung An Hand von sich auf 10 Kristalle und 7 Gläser beziehenden Daten wird die Umrechnung vonC _v -inC _p -Werte für feste lineare Makromoleküle mittels der Nernst-Lindemann-GleichungC _p -C _v =A ₀ C _p ² T/T _m diskutiert. Ein Durchschnittswert vonA ₀=(5.11±2.41) · 10^–3 mol K J^–1 wurde unter der Annahme berechnet, daß sich das Mol nur auf schwere Atome bezieht. DieserA ₀-Wert ist numerisch gleich der ursprünglichen Nerns-Lindemann-Konstanten.

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10 , - C _v C _p , —C _p –C _v = _{0 p} ² / . , , ₀ (5.11±2.41) · 10^–3 · ^–1. ₀ — .

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Support by the National Science Foundation, Polymers Program (Grant No. DMR 83-17097) is gratefully acknowledged.     

Triterpene Glycosides of Fatsia japonica. IV. Structure of Glycosides D1 and D2 from Seeds

Seeds ofFatsia japonica(Araliaceae) afforded the known hederagenin 3-O--D-glucopyranosyl-(12)-O--L-arabinopyranoside and the new triterpene glycoside D ₂ , for which the structure hederagenin 3-O--D- galactopyranosyl-(12)-O--L-arabinopyranoside was proposed based on chemical methods and NMR spectroscopy     

Pressure-jump method in the dehydrogenation of propane over chromia-alumina-potassium oxide

The pressure-jump method was applied to the dehydrogenation of C₃H₈ over a Cr₂O₃–Al₂O₃–K₂O catalyst in a closed static reactor at 443°C. The rate equation proposed for initial kinetics was shown to apply to the dehydrogenation of C₃H₈.

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C₃H₈ Cr₂O₃–Al₂O₃–K₂O 443°C. , , , C₃H₈.

     

Pitzer model parameters for sparingly soluble salts from solubility measurements. The systems TlCl+SrCl2+H2O and TlCl+BaCl2+H2O at 25°C

The solubility of thallium(I) chloride has been determined in aqueous solutions of strontium chloride and barium chloride at concentrations up to 1.5 mol kg^–1. The data were analyzed using Pitzer's equations without making explicit assumption of association to ion pairs by assuming =3 instead of =2, with the ⁽¹⁾ term for TlCl being equivalent to the ⁽²⁾ term for 2-2 electrolytes. Best values of ⁽⁰⁾ and ⁽¹⁾ for TlCl are recommended together with K _s , the activity solubility product. These were used to fit the present solubility data and derive the Pitzer model mixture parameters relevant to the systems, _fTIN and _fTINCl (N=Sr, Ba). Mixture parameters for TlCl+MCl+H₂O systems are also derived to complete the parameter base. The fit of the experimental data was found to be worse when higher-order terms for asymmetrical mixing were included in the analysis. Activity coefficients for thallium(I) chloride in the mixtures are derived.     

Bestimmung der Atomladungen in Molekülen aus der Verschiebung der K α1/α2-Hauptlinie und ihrer Satellitenlinien für Elemente der 3.Periode

Zusammenfassung Mit einem quantenmechanischen Variationsverfahren werden unter Verwendung eines minimalen Basissatzes an STO-Funktionen für die Elemente der 3. Periode: Mg, Al, Si, P die Verschiebungen der K _1/2-Hauptlinie und ihrer Satellitenlinien , , ₃, ₃, ₄ als Funktion des Ionisationsgrades berechnet. Durch Vergleich mit der experimentell bestimmten Verschiebung des K -Satellitenspektrums in Verbindungen lassen sich Informationen über die Elektronenverteilung in der Umgebung dieser Elemente gewinnen. Aus der Verschiebung werden schließlich die effektiven Atomladungen der Elemente in den betreffenden Verbindungen bestimmt.

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Determination of the atomic charges of the 3rd period elements in molecules by means of the displacements of the K -satellites

STO-Calculations are reported for X-ray-transitions of the type K ¹ L ¹L ² for the 3rd period elements Mg, Al, Si, P and some of their ions. Moreover the shift of the K _1/2-satellites as a function of the degree of ionization is compared with the experimental displacements in certain compounds of 3rd period elements. In this way some information results about the electron distribution in the neighbourhood of the emitting atom. We relate the shift to the number of electrons in the outer shell of the atom and determine the effective charges of 3rd period elements in compounds.

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Résumé Calculs STO pour les transitions du spectre X de type K ¹ L ¹L ² pour les éléments de la troisième période Mg, Al, Si, P et certains de leurs ions. De plus le déplacement des satellites K _1/2-en fonction du degré d'ionisation est comparé avec les déplacements expérimentaux dans certains composés des éléments de la troisiéme période. De cette manière on obtient une certaine information sur la distribution électronique au voisinage de l'atome émetteur. Nous relions le déplacement au nombre d'électrons dans la couche externe de l'atome et nous déterminons les charges effectives des éléments de la troisiéme période dans leurs composés.