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  • crystal structure  (2)
  • interatomic distances  (2)
  • molecule  (2)
  • 1,3,4-oxadiazoles  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Journal of Physics and Chemistry of Solids 53 (1992), S. 319-321 
    ISSN: 0022-3697
    Schlagwort(e): Pressure ; chalcogen ; dissociation ; halogen ; hydrogen ; molecule ; oxygen
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Structural chemistry 11 (2000), S. 177-183 
    ISSN: 1572-9001
    Schlagwort(e): van der Waals radius ; molecule ; crystal ; anisotropy ; hydrogen bond
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The anisotropic components of van der Waals radii for 5b, 6b and 7b Group elements were determined from the structures of gaseous van der Waals complexes and of crystalline molecular solids. The transition from the gaseous to the solid state reduces the anisotropy of a van der Waals atomic shape. This anisotropy is largely responsible for the changes of intermolecular distances, which are often misinterpreted as an effect of hydrogen bonds.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1573-9171
    Schlagwort(e): iron(II) and ruthenium(II) complexes ; synthesis ; carbonyl, cyclopentadienyl, benzoate ligands ; crystal structure ; X-ray diffraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Complexes of Fe(II) and Ru(II) of the general formula Cp(OC)2MOC(O)C6H4X-p, where M=Fe, X=H, F (1, 2) or M=Ru, X=H, F (3, 4) have been prepared by reactingp-XC6H4COOAg with [CpFe(CO)2]2 or CpRu(CO)2I. The crystal structures of complexes1–3 have been determined using X-ray diffraction. Compounds1 and3 are isomorphous. The COO group in1–3 is coordinated as a monodentate ligand. As the latter and the CO ligands are electronically non-equivalent, the coordination of the Cp ligand to the metal is slightly asymmetric.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Russian chemical bulletin 43 (1994), S. 588-590 
    ISSN: 1573-9171
    Schlagwort(e): 1,3,4-oxadiazoles ; fluorodinitromethyl derivatives ; synthesis ; X-ray structural method ; polymorphism ; packing density
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract An X-ray structural study of 2,5-bis(fluorodinitromethyl)-1,3,4-oxadiazole (1), one of the representatives of azoles with strong electron-withdrawing substituents, has been carried out. It has been found that in the orthorhombic modification of1 the conformations of the fluorodinitromethyl groups are different. Intermolecular contacts in the crystal are realized through the heterocycles arranged at large angles to each other. The presence of strong electron-withdrawing substituents results in shortening of the C-O bonds and in a certain increase in the OCN angle in the 1,3,4-oxadiazole ring.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Russian chemical bulletin 43 (1994), S. 1300-1304 
    ISSN: 1573-9171
    Schlagwort(e): van der Waals molecules ; van der Waals radii of metals ; polarizability ; dissociation energy ; interatomic distances
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The lack of information about the van der Waals radii of metals can be compensated for by using the results of spectroscopic investigations of van der Waals molecules. It has been shown that the interatomic distances in these molecules obey an additive scheme if one allows for the polarization effects. The van der Waals radii of the alkali metals, Ag, Mg, Zn, Cd, Hg, B, Al, In, and Si, have been determined from the interatomic distances in their heteroatomic molecules with atoms of noble gases. Use of the obtained radii for crystal chemistry is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Russian chemical bulletin 44 (1995), S. 2245-2250 
    ISSN: 1573-9171
    Schlagwort(e): bond lengths ; interatomic distances ; molecular structures ; metals ; covalent radii
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The results of direct experimental determination of covalent bond lengths in molecular structures are presented. This made it possible to establish the values of normal covalent radii. The recommended values of covalent radii for 56 elements are tabulated.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 0947-6539
    Schlagwort(e): crystal structure ; cyclophanes ; electrochemistry ; porphyrazines ; tetrathiafulvalenes ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The pyrazinoporphyrazine system 13 (metal-free, zinc and copper derivatives) has been synthesised by tetramerisation of 2,3-dicyanopyrazine monomer unit 10. The structure of 13a-c has been established by 1H NMR spectroscopy, UV/Vis spectrophotometry, MALDI-TOF mass spectrometry, cyclic voltammetry and differential pulse voltammetry. The electrochemical redox behaviour of 13a-c is strongly solvent dependent. The expected two-stage oxidation of the tetrathiafulvalene (TTF) units of 13a-c was observed in a range of solvents; in addition, oxidation and reduction of the pyrazinoporphyrazine core of the metal-free derivative 13a was detected in benzonitrile. On excitation of 13 in the Q-band region no fluorescence was observed, which is presumably the consequence of intramolecular charge transfer between the TTF moieties and the excited state of the central porphyrazine. Molecular modelling studies on 13a and 13c are reported. During the course of this work, the novel TTF macrocycles 11 and 20 were synthesised; their X-ray crystal structures reveal severely bent TTF units, the conformations of which are discussed in detail. The X-ray crystal structures of the bis(1,3-dithiole) systems 15 and 18 have also been determined.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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