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'Mixed Valence' in keywords Facet   Publication Year 1996  [X]
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1996[X]
1Author    Takahiro Ueda, Nobuo NakamuraRequires cookie*
 Title    Sb NMR and SCF-MS-Xa Studies of Quadrupole Interaction and The Electronic Structure of Mixed-Valence Compound, Cs 2 SbCl 6  
 Abstract    Cs 2 SbCl 6 is known as a typical mixed-valence compound. It crystallizes into a tetragonal space group I4 1 /amd and contains two different complex anions, Sb(III)Cl| _ and Sb(V)Clg . The dark blue color of this compound has been considered to originate from a charge transfer between the above two anions. In order to study the electronic structure of these complex anions and the existence of charge transfer between them we measured the 121 Sb NMR spectrum and carried out molecular orbital calculations on the electronic states of these anions. The 121 Sb NMR spectrum consists of two peaks at 0 and 30 kHz which can be assigned to the central transition of l21 Sb in Sb(V)Cl<~ and Sb(III)Cl| _ , respectively. The line shape analyses of the spectra led to nuclear quadrupole coupling constants of nearly zero for Sb(V)Cl7 and 4.9 ±0.5 MHz for Sb(III)Cl| at room temperature. The quadrupole coupling constant of 1 Sb(III) decreases steadily on heating. The calculations of the electronic ground state energies of both anions were calculated by the MS-Xa molecular orbital method. The calculated charge-transfer band from the A lg state of Sb(III)Clg" to the A lg state of Sb(V)Cl6 appears at 610 nm and can account for the experimental electronic spectrum, the calculated quadrupole coupling constant in Sb(III)Clg" however is far larger than the experimental one. The contribution of the charge-transferred state to the ground state is negligible and so the temperature dependence of the quadrupole coupling constant of 121 Sb(III) is attributed to an anisotropic thermal expansion of the compound. 
  Reference    Z. Naturforsch. 51a, 672—676 (1996); received October 10 1995 
  Published    1996 
  Keywords    NMR, Quadrupole interaction, Molecular orbital, Mixed valence 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0672.pdf 
 Identifier    ZNA-1996-51a-0672 
 Volume    51