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  • Inorganic Chemistry  (10)
  • 65H10  (2)
  • 1985-1989  (11)
  • 1975-1979  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Reduktive Arylierung von Vinyl-trifluoromethansulfonaten durch Friedel-Crafts-Reaktion (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1255-1256 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reductive Arylation of Vinyl Trifluromethanesulfonates by Friedel-Crafts ReactionThe reaction of vinyl triflates 1 with benzene and toluene in the presence of aluminium trichloride gives alkyl-, alkenyl-, and 1,1-diarylalkanes 5, 6, 3, 9 depending on the structure of the substrate used. A mechanism for the reductive arylation is proposed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200724
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  • 2
    Electronic Resource
    Electronic Resource
    Quasi-Newton methods with factorization scaling for solving sparse nonlinear systems of equations (1987)
    Springer
    Computing 38 (1987), S. 133-141 
    Details
    ISSN: 1436-5057
    Keywords: 65H10 ; Nonlinear systems ; Quasi-Newton methods ; sparse matrices ; factorization of matrices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir stellen in dieser Arbeit ein Verfahren vom Quasi-Newton-Typ für große, dünnbesetzte nichtlineare Gleichungssysteme vor, das die QR-Faktorisierung der näherungsweisen Jacobi-Matrix benutzt. Das Verfahren gehört zu einer allgemeinen Klasse von Algorithmen, für die wir die lokale Konvergenz beweisen. Einige numerische Experimente deuten auf die Verläßlichkeit des neuen Algorithmus hin.
    Notes: Abstract In this paper we present a Quasi-Newton type method, which applies to large and sparse nonlinear systems of equations, and uses the Q-R factorization of the approximate Jacobians. This method belongs to a more general class of algorithms for which we prove a local convergence theorem. Some numerical experiments seem to confirm that the new algorithm is reliable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02240178
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  • 3
    Electronic Resource
    Electronic Resource
    Solution of nonlinear systems of equations by an optimal projection method (1986)
    Springer
    Computing 37 (1986), S. 59-70 
    Details
    ISSN: 1436-5057
    Keywords: 65H10 ; Nonlinear equations ; projection methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir betrachten eine Block-Version des Nichtlinearen Projektions-Verfahrens mit einer optimalen Kontrolle. Dieses Verfahren wird zur Lösung von Gleichungssystemen verwendet, bei denen die Gleichungsanzahl kleiner oder gleich der Anzahl der Unbekannten ist. Ein lokaler Konvergenzsatz wird bewiesen. Ein numerischer Vergleich mit dem zyklischen Nichtlinearen Projektions-Verfahren wird angestellt.
    Notes: Abstract We consider a block version of the Nonlinear Projection Method under an optimal control. This method is applied to the solution of systems of equations where the number of equation is less than or equal to the number of unknowns. A local convergence theorem is proved. We present a numerical comparison with the cyclic Nonlinear Projection Method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02252734
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  • 4
    Electronic Resource
    Electronic Resource
    Über Struktur und Stereoselektivität von 2-Norbornen-7-yl-Radikalen und -Carbenoiden (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 4281-4284 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Structure and Stereoselectivity of 2-Norbornen-7-yl Radicals and CarbenoidsReduction of 7,7-diiodonorbornene (1) with Grignard reagents proceeds via the 7-iodo-2-norbornen-7-yl radical 2. From the observed syn-stereoselectivity, the absence of π-delocalization in 2 is inferred. This result agrees with the existence of an equilibrium mixture of two classical pyramidal structures (2a and 2b), in which the syn-isomer 2a predominates. The reaction of 1 with methyllithium takes place with anti-stereoselectivity; this fact proves that the anti-carbenoid 4b-M is more stable than the syn-isomer.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851181035
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  • 5
    Electronic Resource
    Electronic Resource
    Selektivität bei der Umsetzung von Carbokationen mit Nucleophilen, 2. Solvolyse-Mechanismen bei 7-Norbornyl-trifluormethansulfonaten (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2557-2560 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selectivity in the Reaction of Carbocations with Nucleophiles, 2. Solvolytic Mechanisms of 7-Norbornyl TrifluoromethanesulfonatesThe reactions of 7,7-bis(trifluoromethylsulfonyloxy)norbornane (4) with several metal cyanides in dipolar aprotic solvents are studied. The results obtained (Table 1) lead to the conclusion that the solvolysis of 7-substituted 7-norbornyl trifluoromethanesulfonates takes place either according to a kc mechanism or with fission of the S — O bond. In no instance is a C — O fission following an SN2 mechanism to be expected. - The selectivity of the reaction of the intermediate carbocations with nucleophiles cannot be explained by means of N+ correlations nor by the reactivity-selectivity relationship, but can be rationalized according to the HSAB principle.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180632
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  • 6
    Electronic Resource
    Electronic Resource
    On the Tautomerism of 2-Phenacyl-4-pyrimidinones and Related Compounds (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 919-924 
    Details
    ISSN: 0009-2940
    Keywords: Pyrimidinones ; Tautomerism ; AM1 calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zur Tautomerie von 2-Phenacyl-4-pyrimidinonen und verwandten Verbindungen3-Methyl-2-phenacyl-4-pyrimidinone 1, 2 werden durch Sulfidkontraktion synthetisiert. Aufgrund der NMR-Daten existieren die Verbindungen ausschließlich in der Benzoylmethylen-Form, sowohl in Lösung als auch als Festkörper. Diese Ergebnisse werden durch AM1-Berechnungen für die Stammverbindung bestätigt. Die Untersuchung des Tautomeren-Gleichgewichts mittels dieser semiempirischen Methode wurde auf andere Fälle von Enaminoketon/Enolimin-Tautomerie erweitert.
    Notes: 3-Methyl-2-phenacyl-4-pyrimidinones 1, 2 have been synthesized using the sulfide contraction. According to the NMR data, the compounds 1, 2 exist exclusively as the benzoylmethylene tautomers a both in solution and in the solid state. AM1 calculations of the parent system are in agreement with the experimental observations. The study of the tautomeric equilibrium by this semiempirical method has been extended to other cases of enamino-ketone/enolimine tautomerism.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220521
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  • 7
    Electronic Resource
    Electronic Resource
    Mechanismus der Reaktion von Trifluormethansulfonsäureanhydrid mit Ketonen: Umsetzung mit Campher (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1282-1288 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mechanism of the Reaction of Trifluoromethanesulfonic Anhydride with Ketones: Reaction with CamphorReaction of camphor (1) with trifluoromethanesulfonic anhydride (Tf2O) in the absence of base yields a mixture of 2,2-bis(trifluoromethylsulfonyloxy)camphane (9), 1,2-bis(trifluoromethylsulfonyloxy)-endo-isocamphane (10), and 2,4-bis(trifluoromethylsulfonyloxy)-endo-isocamphane (11). The ratio of these compounds depends on the reaction temperature. 9, 10, and 11 could not be isolated because, during the final aqueous treatment, they undergo hydrolysis leading to 1, 1-camphenyl triflate (2), and 4-camphenyl triflate (3). In the presence of 2,6-di-tert-butyl-4-methylpyridine (DTBMP) 2 is the main reaction product. The reaction rate is independent of the base concentration. It can be inferred that the base only neutralized the trifluoromethanesulfonic acid (TfOH), without reaction with Tf2O. - Reaction of 2 with TfOH in dichloromethane takes place with addition and Nametkin rearrangement. The ratio of these reactions depends on the reaction temperature. No rearrangement products are obtained in the reaction of 1 with TfOH. The reaction paths for the reaction of 1 with Tf2O are compared with those for other ketones, and some conclusions on the electronic requirements of the Nametkin rearrangement are inferred.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180344
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  • 8
    Electronic Resource
    Electronic Resource
    Zinc(II), cadmium(II), and mercury(II) halide coordination compounds with 1,8-bis(2-pyridyl)-3,6-dithiaoctane. The crystal and molecular structure of Hg2(C16H20N2S2)Br4 (1988)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 567 (1988), S. 101-110 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Koordinationsverbindungen von Zink (II), Cadmium (II) und Quecksilber(II)-Halogeniden mit 1,8-Di-2-pyridyl-3,6-dithiactan. Kristallstruktur von Hg2(C16H20N2S2)Br4Es werden verschiedene Komplexe von 1,8-Di-2-pyridyl-3,6-dithiaoctan (bpdto) mit MX2 (M = Zn, Cd oder Hg und X = Cl, Br oder I) hergestellt und mittels Elementar-analyse, IR, 1H-NMR und konduktometrischen Messungen untersucht. Die Kristallstruktur von Hg2(bpdto)Br4 wird mit Hilfe von Röntgenbeugungsdaten ermittelt (R = 0,079). Hg2(C16H20N2S2)Br4 kristallisiert monoklin in der Raumgruppe P21/c mit vier Formeleinheiten pro Elementarzelle; Gitterkonstanten a = 14,410(3), b = 6,209(5), c = 14,478(5) Å, β = 113,98(1)°. Im Komplex sind zwei Hg-Atome verzerrt-tetraedrisch koordiniert von je einem S-Atom [Hg—S 2,670(3) Å], einem N-Atom [Hg—N 2,366(8) Å] des verbrückenden Liganden und zwei terminalen Br-Atomen [Hg—Br 2,502(1) und 2,501(2) Å].
    Notes: We describe the synthesis and characterization (by elemental analysis, conductance measurements and 1H NMR and IR spectrometry) of compounds with the general formulae M(bpdto) X2 (M = Zn, X = Cl, Br or I; M = Cd, X = Cl or Br) and M2(bpdto)X4 (M = Cd, X = I; M = Hg, X = Cl, Br or I) (bpdto = 1,8-bis(2-pyridyl)-3,6-dithiaoctane). In addition, the structure of Hg2(bpdto)Br4 was determined by single crystal structure analysis and refined to a conventional R factor of 0.079. Hg2(C16H20N2S2)Br4 crystallized in the monoclinic space group P21/c with a = 14.410(3), b = 6.209(5), c = 14.478(5) Å, β = 113.98(1)° and Z = 4. The molecule was found to have two mercury atoms, each tetrahedrally coordinated to two bromide anions [Hg—Br 2.502(1) and 2,501(2) Å], and to one nitrogen atom [Hg—N 2.366(8) Å] and one sulphur atom [Hg—S 2.670(3) Å] of the ligand molecule, which acted as a bridge between the two metal atoms.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19885670112
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  • 9
    Electronic Resource
    Electronic Resource
    Darstellung, Temperaturverhalten und Kristallstruktur von BiF3 (1977)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 436 (1977), S. 105-112 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation, Temperature Behaviour, and Crystal Structure of BiF3Orthorhombic BiF3 was prepared from BiOCl and HF at 300°C through elimination of oxygen. Thermal analysis showed no transformation up to the melting point of 757°C. The orthorhombic structure of BiF3 can, however, transform into the structure of Tysonit in presence of a small amount of oxygen. The single-crystal X-ray structure determination (553 reflexions, R = 0.050) demonstrated that BiF3 is isostructural with the rare-earth trifluorides of the YF3 type (Pnma). The coordination polyhedron around Bi can be described in terms of a slightly distorted square-antiprisma (CN = 8).
    Notes: Orthorhombisches BiF3 wurde aus BiOCl und Fluorwasserstoff bei 300°C unter Ausschluß von Sauerstoff dargestellt. BiF3 zeigt bis zum Schmelzpunkt bei 757°C keine Phasen-umwandlung. Die orthorhombische BiF3-Struktur kann durch sehr geringe Sauerstoffgehalte in die Tysonitstruktur umgewandelt werden. Die Einkristall-Röntgenstrukturanalyse (553 Reflexe, R = 0,050) ergab, daß BiF3 isotyp mit den Selten-Erd-Trifluoriden vom YF3-Typ (Pnma) ist. Die Koordinationsverhältnisse um Bi können mit Hilfe eines leicht verzerrten quadratischen Antiprismas (KZ = 8) beschrieben werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19774360112
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  • 10
    Electronic Resource
    Electronic Resource
    Complexes of IIB Metal Halides with N,N-Diethylbenzenecarbothioamide crystal structure of [Hg{C6H5C(S)N(C2H5)2}I2]2 (1986)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 539 (1986), S. 219-228 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Komplexe von IIB Metall-halogeniden mit N,N-Diethylbenzocarbothioamiden. Kristallstruktur von [Hg{C6H5C(S)N(C2H5)2}I2]2Verschiedene Komplexe von N,N-Diethylbenzocarbothioamide (DEBCTA) mit MX2 (M = Zn, Cd oder Hg und X = Cl, Br oder I) wurden hergestellt und mittels Elementaranalyse, Molgewichtsbestimmung, IR, 1H-NMR-Spektren und konduktometrischen Messungen untersucht. Die Kristallstruktur von [Hg(DEBCTA)I2]2 wurde mit Hilfe von Röntgenbeugungsdaten ermittelt (2402 beobachtete unabhängige Reflexe, R = 0,097). [Hg(DEBCTA)I2]2 kristallisiert monoklin in der Raumgruppe P21/n mit zwei Formeleinheiten pro Elementarzelle; Gitterkonstanten a = 1383,9(2), b = 834,3(1), c = 1 418,1(2) pm, β = 101,03(1)°. Im dimeren Komplex sind die verzerrt-tetraedrisch koordinierten Hg-Atome von je einem S-Atom des Liganden, einem terminalen I-Atom und zwei verbrückenden I-Atomen umgeben.
    Notes: Complexes having the empirical formulae M(DEBCTA)2X2 (M = Zn or Cd, X = Br or I, DEBCTA = N,N-diethylbenzenecarbothioamide), Zn(DEBCTA)Cl2, Cd2(DEBCTA)Cl4 and Hg(DEBCTA)X2 (X = Cl, Br or I) were made by reaction of zinc, cadmium or mercury dihalides in ethanol or 1,2-dichloroethane. All complexes have been characterized by elemental analysis, conductance and molecular weight measurements and by infrared and 1H-NMR spectral studies. In addition, the structure of [Hg(DEBCTA)I2]2 has been determined by single-crystal X-ray crystallography and refined to a conventional R factor of 0.097. The compound crystallizes in the monoclinic space group P21/n with a = 1383.9(2), b = 834.3(1), c = 1418.2(2) pm, β = 101.03(1)° and Z = 2. The molecule was found to have a dimeric structure involving two asymmetrical iodine bridges in which the Hg atom lies a tetrahedral environment and the ligands lie mutually trans with respect to one another.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19865390823
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