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2000 (2)
1999 (1)
1Author    Z. Akdeniz, M. P. TosiRequires cookie*
 Title    Structure and Vibrational Spectra of the Vapour Molecules Fe 2 Cl 6 and AlFeCl 6  
 Abstract    Melting of aluminium and iron trichloride crystals is accompanied by a structural transition from octa-hedral to tetrahedral coordination of the metal ions, and a widely accepted interpretation of their liquid structure is that it mainly consists of strongly correlated dimeric units. Such A1 2 C1 6 and Fe 2 Cl 6 mole-cules are stable in the vapour phase and coexist in gaseous mixtures together with AlFeCl 6 molecules. In this work we extend to Fe 2 Cl 6 and AlFeCl 6 our earlier study of the ionic interactions in A1 2 C1 6], using a model which accounts for ionic deformability through (i) effective valences and (ii) electrostatic and overlap polarizabilities. The main disposable parameters of the model are adjusted to the Fe-Cl bond length in FeCl 3 monomer molecule and to the Fe-Fe bond length and a bond-stretching frequency in the Fe 2 Cl 6 molecule. The results are used to evaluate the structure of the AlFeCl 6 molecule, which has so far only been inferred from the observed Raman spectrum in mixed vapours. Extensive comparisons with data on molecular vibration-al frequencies are also presented for Fe 2 Cl 6 and AlFeCl 6 . 
  Reference    Z. Naturforsch. 54a, 477—481 (1999); received August 3 1999 
  Published    1999 
  Keywords    Ionic Clusters, Molecular Vapours, Molten Salts 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0477.pdf 
 Identifier    ZNA-1999-54a-0477 
 Volume    54 
2Author    Z. Akdeniz, M. P. TosiRequires cookie*
 Title    Static and Dynamic Structure of AU 2 C1 6 , AUA1C1 6 and AuFeCl 6 Clusters  
 Abstract    Fourfold coordination of trivalent metal ions by chlorines in molecular dimers changes from tetrahedral in A1 2 C1 6 and Fe 2 Cl 6 to planar in Au 2 Cl 6 . Within an ionic model we interpret this transition in the stable molecular shape as due to the quadrupolar polarizability of the gold(III) ion. We also demonstrate within the same model that a mixed tetrahedral-planar coordination is stable in AUA1C1 6 and AuFeCl 6 clusters. Quantitative comparisons are presented for the calculated molecular structures and vibrational frequencies against the available experimental data from crystalline diffraction and from Raman spectra of the crystal and of vapours. 
  Reference    Z. Naturforsch. 55a, 495—198 (2000); received February 12 2000 
  Published    2000 
  Keywords    Ionic Clusters, Molecular Vapours, Molecular Crystals 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0495.pdf 
 Identifier    ZNA-2000-55a-0495 
 Volume    55 
3Author    Z. Akdeniz, M. Çaliskan, Z. Çiçek, M. P. TosiRequires cookie*
 Title    Polymerie Structures in Aluminium and Gallium Halides  
 Abstract    The anionic species (Al" X3 n+ iwith X = CI or Br and n > 1 have been recognized for a number of years to form in acidic liquid mixtures of aluminium chloride or bromide with the corresponding halides of alkali or organic cations, in relative proportions which vary with the composition of the mixture. In this work we evaluate the structure and the energetics of such polymeric series in a comparative study of Al and Ga compounds. To this end we first extend an earlier study of the ionic interactions in the A1 2 C1 6 molecule] to determine microscopic ionic models for Ga 2 Cl 6 , Al 2 Br 6 , and Ga 2 Br 6 . The models are then used (i) to evaluate the polymeric clusters for n < 4 in the two trivalent-metal chlorides, and (ii) to explore the potential-energy hypersurface of alkali counterions in the case n = 2. We present tests of the results against available data and an evaluation of the convergence of the energy of the polymeric series towards a value of about 0.5 eV per monomer. 
  Reference    Z. Naturforsch. 55a, 575—580 (2000); received February 18 2000 
  Published    2000 
  Keywords    Ionic Clusters, Molecular Vapours, Molten Salts 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0575.pdf 
 Identifier    ZNA-2000-55a-0575 
 Volume    55