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  • Inorganic Chemistry  (6)
  • Computational Chemistry and Molecular Modeling  (3)
  • 42.75
  • Capillary electrophoresis
  • Nederland
  • 1995-1999  (10)
  • 1960-1964
  • 1996  (10)
Collection
Publisher
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  • 1995-1999  (10)
  • 1960-1964
Year
  • 1
    ISSN: 0009-2940
    Keywords: Organotungsten selenolates ; 77Se NMR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organotungsten-selenolato complexes were prepared in moderate yields by insertion of selenium into the alkali metaltungsten bonds of MSeW(CO)3cp (M = Li, Na) and subsequent reactions with the organohalides o-, m-, and p- C6H4(CH2Br)2, C6H5CHBr2, m-C6H4(CHBr2)2 and C6H5CCl3. The 77Se-NMR data of the new complexes are discussed and compared with those of related complexes derived from organomonohalides. Moreover, the X-ray crystal structures of C6H5CH2W(CO)3cp (1), μ-[m-C6H4{CH2SeW(CO)3cp}2] (3), μ-[p-C6H4{CH2SeW(CO)3cp}2] (4), and C6H5CH[SeW-(CO)3cp]2 (5) were determined. In complex (1), the W-CH2 bond length is 2.374 Å; the W-Se bond lengths in the complexes 3, 4 and 5 are all in the range 2.625-2.655 Å, corresponding to W-Se single bonds.
    Additional Material: 3 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 99-104 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Micellear electrokinetic chromatography ; Organic modifiers ; Naphthalene sulfonates ; Surface water ; Thermostatting ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The production and use of naphthalene sulfonates can easily cause pollution of surface and other types of waters. In the present study, capillary electrophoresis in combination with UV absorption detection was used to separate 21 amino- and hydroxy-substituted naphthalene sulfonates which included multiple isomeric compounds. The influence of various parameters such as pH (which turned out to be extremely important), temperature of the surrounding air flow, and the use of buffer additives (micelles, cyclodextrins, organic modifiers) was studied. Complete separation of all analytes including the isomers, was achieved in two runs with a 50 mM boric acid/borate buffer, containing either 100 mM sodium dodecylsulfonate or 15% acetonitrile. The limits of detection obtained for the individual compounds typically were 20μgI-1. River water samples spiked at this concentration level could be analysed using a simple three-step sample clean-up procedure.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1067-1076 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solvent shift of the π* ← n transition of acetone in water, acetonitrile, and tetrachloromethane was calculated in a combined quantum mechanical - classical mechanical approach, using both dielectric continuum and explicit, polarizable molecular solvent models. The explicit modeling of solvent polarizability allows for a separate analysis of electrostatic, induction, and dispersion contributions to the shifts. The calculations confirm the qualitative theories about the mechanisms behind the blue shift in polar solvents and the red shift in nonpolar solvents, the solvation of the ground state due to electrostatic interactions being preferential in the former, and favorable dispersion interaction with the excited state, in the latter case. Good quantitative agreement for the solvent shift between experiment (+1,700, +400, and -350 cm-1 in water, acetonitrile, and tetrachloromethane, respectively) and the explicit solvent model (+1,821, +922, and -381 cm-1) was reached through a modest Monte Carlo sampling of the solvent degrees of freedom. A consistent treatment of the solvent could only be realized in the molecular solvent model. The dielectric-only model needs reparameterization for each solvent. © 1996 John Wiley & Sons, Inc.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 185-192 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simplified LCAO-DFT-LDA scheme for calculations of structure and electronic structure of large molecules, clusters, and solids is presented. Forces on the atoms are calculated in a semiempirical way considering the electronic states. The small computational effort of this treatment allows one to perform molecular dynamics (MD) simulations of molecules and clusters up to a few hundred atoms as well as corresponding simulations of condensed systems within the Born-Oppenheimer approximation. The accuracy of the method is illustrated by the results of calculations for a series of small molecules and clusters. © 1996 John Wiley & Sons, Inc.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 1111-1132 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct reaction field (DRF) force field gives a classical description of intermolecular interactions based on ab initio quantum-chemical descriptions of matter. The parameters of the DRF force field model molecular electrostatic and response properties, which are represented by distributed charges and dipole polarizabilities. The advantage of the DRF force field is that it can be combined transparently with quantum-chemical descriptions of a part of a large system, such as a molecule in solution or an active site in a protein. In this study, the theoretical basis for the derivation of the parameters is reviewed, paying special attention to the four interaction components: electrostatic, induction, dispersion, and repulsion. The ability of the force field to provide reliable intermolecular interactions is assessed, both in its mixed quantum-chemical-classical and fully classical usage. Specifically, the description of the water dimer and the solvation of water in water is scrutinized and seen to perform well. The force field is also applied to systems of a very different nature, viz. the benzene dimer and substituted-benzene dimers, as well as the acetonitrile and tetrachloromethane dimers. Finally, the solvation of a number of polar solutes in water is investigated. It is found that as far as the interaction energy is concerned, the DRF force field provides a reliable embedding scheme for molecular environments. The calculation of thermodynamic properties, such as solvation energy, requires better sampling of phase space than applied here. © 1996 John Wiley & Sons, Inc.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 2074-2078 
    ISSN: 0044-2313
    Keywords: μ-oxo bis [pentaammine vanadium(III)] iodide monoammoniate ; μ-oxo bis [pentaammine titanium(III)] iodide monoammoniate ; preparation ; crystal structure ; IR spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung, Kristallstruktur und IR-spektroskopische Untersuchungen an [(NH3)5V—O—V(NH3)5]I4 · NH3 und [(NH3)5Ti—O—Ti(NH3)5]I4 · NH3Reaktionen von VI2 bzw. TiI3 mit Ammoniak in Gegenwart von Wasser- bzw. Sauerstoffspuren führen zu [(NH3)5M—O—M(NH3)5]I4 · NH3 mit M = V, Ti. Ihre Strukturen wurden röntgenographisch an Einkristallen bestimmt:Pbca (Nr. 61), Z = 4, M = V: a = 12,482(4) Å, b = 14,819(6) Å, c = 13,286(5) Å, Z(Fo2 ≤ 3σFo2) = 983, Z(Variablen) = 88, R/Rw = 0,053/0,063, M = Ti: a = 12,628(4) Å, b = 14,970(4) Å, c = 13,359(3) Å, Z(Fo2 ≤ 3σFo2) = 1188, Z(Variablen) = 88, R/Rw = 0,043/0,047Die Strukturen bauen sich aus Oktaederdoppeleinheiten [(NH3)5M—O—M(NH3)5]4+ mit ekliptischer Konformation auf, deren verbrückende Sauerstoffatome nach dem Motiv einer verzerrten, kubisch flächenzentrierten Packung angeordnet sind. IR-spektroskopische Daten von undeuterierten und zu 5% deuterierten Proben der Vanadiumverbindung weisen auf N—H … I-Wasserstoffbrückenbindungen und π-Bindungsanteile zwischen dem jeweiligen Übergangsmetall und dem verbrückenden Sauerstoffatom hin.
    Notes: The reaction of VI2 or TiI3, respectively, with ammonia in the presence of traces of water or oxygen, respectively, leads to [(NH3)5M—O—M(NH3)5]I4 · NH3 with M = V, Ti. Their structures were solved by X-ray single crystal data:Pbca (No. 61), Z = 4, M = V: a = 12.482(4) Å, b = 14.819(6) Å, c = 13.286(5) Å, N(Fo2 ≤ 3σFo2) = 983, N(variables) = 88, R/Rw = 0.053/0.063, M = Ti: a = 12.628(4) Å, b = 14.970(4) Å, c = 13.359(3) Å, N(Fo2 ≤ 3σFo2) = 1188, N(variables) = 88, R/Rw = 0.043/0.047.The structures consist of corner sharing octahedra double units [(NH3)5M—O—M(NH3)5]4+ with eclipsed conformation which are stacked together according to the motif of a distorted cubic face centered arrangement for the bridging oxygen atoms. IR spectroscopic investigations of the undeuterated vanadium compound and of 5% deuterated samples hint to N—H … I hydrogen bridge bonds and to remarkable π-bonding between the transition metal and the bridging oxygen atoms.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 401-404 
    ISSN: 0044-2313
    Keywords: Strontium amalgam, Sr3Hg2 ; crystal structure ; U3Si2 type ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die Verfeinerung der Kristallstruktur des Sr3Hg2Aus Mischungen von Strontium und Quecksilber im Molverhältnis 7:3 kann man durch Tempern bei 520°C (20 Tage) phasenreine Proben von Sr3Hg2 erhalten, aus denen Einkristalle ausgelesen werden können. Sr3Hg2 kristallisiert im U3Si2-Typ (Raumgruppe P4/mbm) mit a = 8,883(2) Å und c = 4,553(1) Å. Alle Hg-Atome sind in Hanteln eingebunden (dHg—Hg = 3,41 Å).
    Notes: Mixtures of strontium and mercury in molar ratios of 7:3 have been annealed for 20 days at 520°C. From the pure product Sr3Hg2 single crystals have been obtained. Sr3Hg2 crystallizes in the U3Si2 type of structure (space group P4/mbm); the cell constants are a = 8.883 (2) Å and c = 4.553(1) Å. All of the Hg atoms are involved in Hg2 dumbbells with Hg—Hg distances of 3.41 Å.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 254-258 
    ISSN: 0044-2313
    Keywords: Iron cerium oxotungstate, FeCe(WO4)3 ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A New Structure Type for the Rare Earth Oxotungstate FeCe(WO4)W2O8 = FeCe(WO4)3Single crystals of the hitherto unknown compound FeCe(WO4)3 have been prepared by crystallization from melts of Fe2O3, CeO2 and WO3. It crystallizes with triclinic symmetry, space group P1, a = 7,486(3); b = 7,528(1); c = 16,502(4) Å, α = 101,00(2); β = 96,62(3); γ = 98,62°; Z = 2. Tungsten shows octahedral and tetrahedral coordination by oxygen. The crystal structure is characterized by layers related to the Scheelite and Wolframite type. Thermogravimetric measurements led to a lost of oxygen during reaction. It results in a decrease of the oxidation states of Fe3+ and Ce4+ respectively, as will be discussed using magnetic measurements and calculations of the Coulomb terms of lattice energy. The structure contains a one-fold coordinated oxygen.
    Notes: Einkristalle der bisher unbekannten Verbindung FeCe(WO4)3 wurden aus Schmelzen von Fe2O3, CeO2 und WO3 erhalten und röntgenographisch untersucht. Sie kristallisieren mit trikliner Symmetrie, Raumgruppe P1, mit a = 7,486(3); b = 7,528(1); c = 16,502(4) Å, α = 101,00(2); β = 96,62(3); γ = 98,62(2)°, Z = 2. Wolfram ist oktaedrisch und tetraedrisch von O2- koordiniert. Im Kristallverband sind Polyederschichten zu erkennen, die sich vom Scheelit und Wolframit ableiten. Thermogravimetrische Messungen zeigen Sauerstoffabgabe während der Reaktion. Die damit verbundene Erniedrigung der Oxidationszahl von Fe3+ bzw. Ce4+ wird anhand magnetischer Messungen und Berechnungen der Coulomb-Terme der Gitterenergie diskutiert. Die Kristallstruktur weist einfach koordinierten Sauerstoff auf.
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  • 9
    ISSN: 0044-2313
    Keywords: Tris(fluorophenyl)antimony and -bismuth compounds ; bismuth tris(2,6-difluorobenzoate) ; preparations ; crystal structure of tris(2,6-difluorophenyl)bismuth ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses and Properties of Some New Tris(fluorophenyl)antimony and -bismuth Compounds. Crystal Structure of Tris(2,6-difluorophenyl)bismuth(2,6-F2C6H3)3Bi, (2,4,6-F3C6H2)3Bi, and (2,6-F2C6H3)3Sb are prepared via Grignard reactions with BiBr3 and SbBr3, respectively. The syntheses and properties of the new compounds and the crystal structure of (2,6-F2C6H3)3Bi are described. From the reaction of BiBr3 with Ag(OCOC6H3F2) the bismuth benzoate Bi(OCOC6H3F2)3 is formed in 83% yield. Attempts to prepare (2,6-F2C6H3)3Bi by decarboxylation of the bismuth benzoate failed.
    Notes: (2,6-F2C6H3)3Bi, (2,4,6-F3C6H2)3Bi und (2,6-F2C6H3)3Sb werden durch Grignard-Reaktionen mit BiBr3 bzw. SbBr3 dargestellt. Die Synthesebedingungen und die Eigenschaften der neuen Verbindungen sowie die Kristallstruktur von (2,6-F2C6H3)3Bi werden beschrieben. Bi(OCOC6H3F2)3 entsteht in 83% Ausbeute aus BiBr3 und Ag(OCOC6H3F2); die präparative Darstellung von (2,6-F2C6H3)3Bi durch Decarboxylierung des Bismutbenzoats gelingt nicht.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 2079-2082 
    ISSN: 0044-2313
    Keywords: Calcium imide CaNH ; preparation ; single-crystals ; structure determination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of Calcium Imide, CaNHSingle-crystals of calcium imide were obtained for the first time by the reaction of a mixture of calcium amide with sodium amide at 850°C in an autoclave for salt melts. After cooling the autoclave to room temperature the crystals are embedded in solid Na which was extracted by liquid ammonia. The structure of calcium imide was determined from single-crystal diffractometer data:space group Fm3m, Z = 4, a = 5.143(1) Å, R/Rw = 0.032/0.028 mit N(Fº2 ≤ 3σ(Fº2)) = 26, N(Var.) = 5.Ca and N atoms are arranged in the motif of the NaCl structure type. The hydrogen atoms of the imide groups are disordered within the Ca octahedra, and they occupy a six fold split position.
    Notes: Kristalle von Calciumimid wurden durch Aufheizen eines Gemenges von Calcium- und Natriumamid in einem Autoklav für Salzschmelzen auf 850°C zum ersten Mal erhalten. Nach Abkühlen des Autoklavs sind die Kristalle in festem Na eingebettet, das mit flüssigem NH3 extrahiert wurde. Die Struktur von CaNH wurde röntgenographisch aus Einkristall-Diffraktometerdaten bestimmt:Raumgruppentyp Fm3m, Z = 4, a = 5,143(1) Å, R/Rw = 0,032/0,028 mit N(Fº2 ≤ 3σ(Fº2)) = 26, N(Var.) = 5.Ca- und N-Atome sind nach dem Motiv des NaCl-Strukturtyps angeordnet. Die Wasserstoffatome der Imidgruppen sind fehlgeordnet und besetzen in den Oktaedern von Ca eine Splitlage mit sechs Aufenthaltsmaxima.
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