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  • 1
    Electronic Resource
    Electronic Resource
    Strukturen ladungsgestörter oder räumlich überfüllter Moleküle. 15. Tetracyanethen-Natrium-Dimethoxyethan (1992)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 614 (1992), S. 109-114 
    Details
    ISSN: 0044-2313
    Keywords: Tetracyanoethene radical anion salt ; single crystal structure ; MNDO calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structures of Charge-Perturbed or Sterically Overcrowded Molecules. 16. Tetracyanoethylene Sodium DimethoxyethaneThe Single crystal structure of [(NC)2C—C(CN)2⊖·Na⊕(H3CO—CH2CH2—OCH3)]∞ reveals two formula units within the triclinic (P1) unit cell. The tetracyanoethylene radical anions are arranged along parallel double layers, which are shifted relative to each other, and in between which are interspersed the sodium counter cations and their dimethoxyethane ligands. The distances within the double layers amount to 300 pm and the ones between them to 385 pm. The six-fold coordinated Na⊕ centers are surrounded by four radical anions with contact distances Na…N between 250 and 254 pm as well as by a twofold solvent ligand with Na…O of 238 and 241 pm. Due to the electron transfer to the acceptor molecule, its (NC)2C-halves twist by 8° and the bond lengths of the N≡C—C subunits, bent by each 3°, are shortened up to 2 pm. The structural parameters are compared to those of the analogous potassium salt [TCNE⊖K⊕DME], of the dianion , of the sodium salts [(NC)3C⊖Na⊕]∞ as well as [(NC)2C—C(CHCH)2—C(CN)2⊖Na⊕]∞ and, in addition, are discussed based on geometry-optimized MNDO calculations.
    Notes: Die Einkristallstruktur von [(NC)2 C — C(CN)2 ⊖ · Na⊕(H3CO—CH2CH2—OCH3)]∞ belegt zwei Formeleinheiten in der triklinen (P1) Einheitszelle. Die Tetracyanethen-Radikalanionen sind entlang paralleler und gegeneinander versetzter Doppelschichten angeordnet, in denen die Natrium-Gegenionen und deren Dimethoxyethan-Liganden eingelagert sind. Der Abstand innerhalb der Doppelschichten beträgt 300 pm, der zwischen ihnen 385 pm. Die sechsfach koordinierten Na⊕-Zentren werden von vier Radikalanionen mit Kontaktabständen Na…N zwischen 250 pm und 254 pm sowie von einem zweizähnigen Solvensliganden mit Na…O von 238 und 241 pm umgeben. Durch den Elektronentransfer auf das Akzeptormolekül verdrillen sich dessen (NC)2C-Hälften um 8° gegeneinander und die Bindungslängen der um 3° geknickten N≡C—C-Einheiten verkürzen sich um bis zu 2 pm. Die Strukturparameter werden mit denen des analogen K⊕-Salzes w[TCNE⊖K⊕DME], des Dianions , der Natrium-Salze [(NC)3C⊖Na⊕]∞ sowie [(NC)2C—C(CHCH)2 — C(CN)2 ⊖ Na⊕]∞ verglichen und zusätzlich anhand geometrieoptimierter MNDO-Berechnungen diskutiert.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19926140819
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  • 2
    Electronic Resource
    Electronic Resource
    Die verschiedenartigen Konformationen N-Trimethylsilyl-substituierter p-Phenylendiamin-Derivate: Untersuchungen an Einkristallen sowie in der Gasphase (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 55-65 
    Details
    ISSN: 0009-2940
    Keywords: Organosilicon p-phenylenediamine derivatives ; Wurster's blue ; PE spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structures of Sterically Overcrowded and Charge-Perturbed Molecules, 38[1].  -  The Different Conformations of N-Trimethylsilyl-Substituted p-Phenylenediamine Derivatives: Investigation of Single Crystals and in the Gas PhaseThe ESR-proven generation of a Wurster's Blue radical anion by one-electron reduction of N,N,N′,N′-tetrakis(trimethylsilyl)-p-phenylenediamine is rationalized by a posterior singlecrystal structure determination of the neutral molecule, which demonstrates inter alia that the bulky [(H3C)3Si]2N substituents are twisted out of the benzene plane by 83°. In contrast, the skeleton of the sterically congested N,N′-bis(trimethylsilyl)-p-phenylenediamine remains almost planar and, accordingly, allows nN/π interaction between the p-type nitrogen electron pairs of the also flattened [(H3C)3Si]HN groups and the benzene π system. These conformational differences are reflected in the gas-phase photoelectron spectra, in which nN/π ionisation bands are split by less than 1 eV or more than 3 eV, respectively. The evidence for analogous structures of the two organosilicon p-phenylenediamine derivatives in solution is confirmed by geometry-optimized AM1 calculations, which readily explain the surprising insertion of an extra electron into an already electron-rich molecule.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270109
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  • 3
    Electronic Resource
    Electronic Resource
    Interactions in Molecular Crystals, 118. The Sodium(benzo-15-crown-5) Salt of 2, 6-Di(tert-butyl)-4-methylphenol, a Sodium Phenolate with an Extremely Short Na+…O- Distance: Structure and Density Functional Calculations (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1533-1537 
    Details
    ISSN: 0009-2940
    Keywords: 2,4,6-Trialkylphenol deprotonation ; Sodium/benzo-15-crown-5 solvation ; Crystal structure ; Density functional calculation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of crystals, isolated in low yield, from the attempted metallation of diphenylmethane in tetrahydrofuran solution containing benzo-15-crown-5 at a sodium metal mirror is determined, surprisingly, to be the sodium (benzo-15-crown) salt of 2,6-di(tert-butyl)-4-methylphenol, an antioxidative stabilizer to prevent ether peroxide formation. The structure of the solvent-shared contact ion pair (monoclinic P21/n, Z = 4, R1 = 0.06) proves a strong Na+…O- interaction at the extremely short distance of only 216 pm, a sixfold O-coordination of the Na+ cation in a pentagonal pyramid, and a hemispherical distortion of the crown ether. Density functional calculations at the B3LYP/6-31G* level, based on the structural data, reproduce, within a one-dimensional hypersurface approach, the rather short Na+…O- distance, and predict Mulliken charges of +0.32 for Na′ and -0.71 for 0-, as well as a considerable polarization of the trialkyl phenolate anion.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301029
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  • 4
    Electronic Resource
    Electronic Resource
    Thianthren-Radikalkation-Tetrachloroaluminat (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2043-2049 
    Details
    ISSN: 0009-2940
    Keywords: Thianthrene radical cation salt ; Crystallization ; Calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structures and Molecular Properties of Charge-Perturbed Molecules, 53[1,2].  -  Thianthrene Radical Cation TetrachloroaluminateOne-electron oxidation of thianthrene, which exhibits a reversible half-wave potential at + 1.3 V and an irreversible one at + 1.65 V, under aprotic conditions with AlCl3/H2CCl2 yields the violet radical cation salt [H4C6S2C6H4⊕][AlCl4⊖]. Its single-crystal structure analysis at 90 K reveals an interplanar angle between the phenyl rings of 174° and demonstrates that the neutral sulfur heterocyclic molecule, bent by 128°, is considerably flattened upon one-electron removal. Semiempirical enthalpy of formation hypersurfaces allow to rationalize the experimental results by a double-minimum potential for the bent neutral molecule with a rather low inversion barrier and a single minimum one for a planar radical cation. Other radical cation properties such as the spin distribution deduced from its ESR spectrum or the visible absorption maxima near \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \nu $\end{document} = 11000 and at 18250 cm-1 corresponding to π → π* and π → σ* transitions are also satisfactorily reproduced by PM3 calculations partly including configuration interaction based on the experimental structure.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271029
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