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1987 (1)
1Author    W. Alter, Abriel, Ernst-Jürgen, Z. EhnderRequires cookie*
 Title    Vibronische Kopplung und dynamisch verzerrte Strukturen in Hexahalogenotelluraten(IV): Ergebnisse aus Tieftemperatur-Röntgenbeugungsuntersuchungen (300—160 K) und aus FTIR-spektroskopischen Experimenten (300—5 K) [1] Vibronic Coupling and Dynamically D istorted Structures in Hexahalogenotellurates(IV): Low Tem peratur X-Ray Diffraction (300—160 K) and FTIR-Spectroscopic (300—5 K) Results [1]  
 Abstract    From theoretical considerations a dynamically distorted octahedron as a result of vibronic coupling between the ground state and the first excited state should exist for 14 electron AX6E systems like TeX62-. A high symmetry crystal field yielding at least a center of symmetry for the Te position stabilizes this fluctuating structure, otherwise statical distortion will be observed. From X-ray diffraction experiments on antifluorite type compounds A 2TeX6 (A = Rb, Cs; X = Cl, Br) the averaged structure (m 3m symmetry) of the anions was found even at very low temperatures. The thermal parameters are not significantly different from those of similar S n X ^ -compounds. Distortions therefore are very small and are evident from FTIR spectroscopic meas­ urements only. Here very broad T lu-deformation vibration bands are observed down to tempera­ tures <10 K without splitting: A statically distorted species could not be frozen out. In contrast to XeF6 for TeX62~ the energy gap between the threefold, fourfold or sixfold minima of the potential surface (according to the symmetry of one component of the T ,u-vibration) is very small and shifted to temperatures lower than reached with the devices used for these experiments. 
  Reference    Z. Naturforsch. 42b, 1273—1281 (1987); eingegangen am 24. Juni 1987 
  Published    1987 
  Keywords    Lone Pair Electrons, Vibronic Coupling, Pseudo Jahn-Teller-Effect, Tellurates 
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 TEI-XML for    default:Reihe_B/42/ZNB-1987-42b-1273.pdf 
 Identifier    ZNB-1987-42b-1273 
 Volume    42