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'Ab initio MO Calculations' in keywords
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2001 (1)
1999 (1)
1Author    Hideta Ishihara, Toshiya Okajima, Keizo Horiuchia, Ingrid Svobodab, Hartmut FuessbRequires cookie*
 Title    Isolated versus Condensed Anion Structure VII: X-ray Structure Analysis of 1,3-Propanediammonium Dibromodichlorocadmate(II), [H3N(CH2)3NH3]CdBr2Cl2, and Estimation of Stability of Five-coordinated Halide Anions, MXg3-(M = Cd, Zn; X = Cl, Br) by Means of Ab-initio MO Calculations  
 Abstract    The coordination capability of Cl and Br in halogenocadmate(II) complexes is estimated by a solution of the structure of 1,3-propanediammonium dibromodichlorocadmate(II). The compound crystallizes as a layered anion structure with Cl bridges and Br terminals at 293 K: Imma, a = 741.56(7), b = 1869.5(5), and c -771.55(8) pm, Z = 4. In order to explain the stronger tendency of halogenocadmate(II) complexes to form layered structures as compared to halogenozincate(II), ab-initio calculations were performed. The stability of MX53-(M = Cd, Zn; X = Cl, Br) is compared. Isolated ZnX53-and CdBr53-ions are not stable. On the other hand a trigonal bipyramid CdCl53-ion is considered to be subtly stable in the crystal mainly due to Coulomb attractive interactions between the positively charged metal cation Cd2+ in a CdCl3 " fragment and two Cl-ions. 
  Reference    Z. Naturforsch. 56a, 641—646 (2001); received June 16 2001 
  Published    2001 
  Keywords    Crystal Structure, Halogenocadmate(II), Ab-initio MO Calculations 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0641.pdf 
 Identifier    ZNA-2001-56a-0641 
 Volume    56 
2Author    Takahiro Ueda, Shigenori Nagatomo, Hirotsugu Masui, Nobuo Nakamura, Shigenobu HayashiRequires cookie*
 Title    Hydrogen Bonds in Crystalline Imidazoles Studied by 15 N NMR and ab initio MO Calculations  
 Abstract    Intermolecular hydrogen bonds of the type N-H...N in crystals of imidazole and its 4-substituted and 4,5-disubstituted derivatives were studied by 15 N CP/MAS NMR and an ab initio molecular orbital (MO) calculation. In the 15 N CP/MAS NMR spectrum of each of the imidazole derivatives, two peaks due to the two different functional groups, >NH and =N-, were observed. The value of the I 5 N isotrop-ic chemical shift for each nitrogen atom depends on both the length of the intermolecular hydrogen bond and the kind of the substituent or substituents. It was found that the difference between the experimen-tal chemical shifts of >NH and =N-varies predominantly with the hydrogen bond length but does not show any systematic dependence on the kind of substituent. The ab initio MO calculations suggest that the hydrogen bond formation influences the 15 N isotropic chemical shift predominantly, and that the difference between the 15 N isotropic chemical shift of >NH and =N-varies linearly with the hydrogen bond length. 
  Reference    Z. Naturforsch. 54a, 437—442 (1999); received March 31 1999 
  Published    1999 
  Keywords    15 N CP/MAS NMR, Imidazoles, Hydrogen Bond, 15 N Chemical Shift, ab initio MO Calculation 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0437.pdf 
 Identifier    ZNA-1999-54a-0437 
 Volume    54