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1994 (1)
1992 (2)
1Author    Toshiyuki Takamuku, Kazumasa Yoshikai, Toshio Yamaguchi, Hisanobu WakitaRequires cookie*
 Title    Structure of Supercooled Aqueous Zinc(II) Bromide Solutions by Raman and X-Ray Scattering Methods  
 Abstract    The structure of aqueous zinc(II) bromide solutions with [H 2 0]/[ZnBr 2 ] molar ratios 5 and 10 in the supercooled state and at ambient temperature has been investigated by Raman spectroscopy and X-ray scattering. Raman spectra of glassy solutions have also been measured for comparison. The Raman and X-ray data suggest that tetrabromo and hexaaqua zinc(II) complexes are favoured in the supercooled and glassy state, while dibromo-and tribromozinc(II) complexes are formed as main species in the solutions at ambient temperature. Probably the reactions 2 [ZnBr 2 (OH 2)] + 2H 2 0 [ZnBr 4 ] 2 ~ + [Zn(OH 2) 6 ] 2 + 4[ZnBr 3 (OH 2)]~ + 2H 2 0 -> 3[ZnBr 4 ] 2 ~ + [Zn(OH 2) 6 ] 2 + occur in the supercooled and glassy solutions. These equilibrium shifts are discussed. 
  Reference    Z. Naturforsch. 47a, 841—848 (1992); received April 24 1992 
  Published    1992 
  Keywords    Supercooled solution, Zinc(II) bromide, Raman spectroscopy, X-ray diffraction, Structure 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0841.pdf 
 Identifier    ZNA-1992-47a-0841 
 Volume    47 
2Author    Toshiyuki Takamuku, Mikito Ihara, Toshio Yamaguchi, Hisanobu WakitaRequires cookie*
 Title    Raman Spectroscopic and X-ray Diffraction Studies on Concentrated Aqueous Zinc (II) Bromide Solution at High Temperatures  
 Abstract    Raman and X-ray scattering experiments have been performed on an aqueous zinc (II) bromide solution with molar ratio [H20]/[ZnBr2] = 10 at 25 to 140 °C. The intensity of the totally symmetric Zn-Br stretching vibration (v^ for the dibromozinc(II) complex increased with increasing temper-ature while that for the tetrabromo complex decreased. A broad band assigned to the symmetric Zn-O stretching vibration (vj for the aqua zinc (I I) ion decreased in intensity with increasing temperature. The X-ray diffraction data revealed that the average number of the Zn-Br interactions within the zinc (II) bromo complexes does not change with temperature, whereas the number of Br • • • Br nonbonding interactions within the complexes decreases from 1.8 at 25 °C to 1.5 at 100 °C. From both Raman and X-ray data it is concluded that with increasing temperature the dibromo species is favored, whereas the tetrabromo and aqua zinc(II) species are unstable in the solution. The analysis of the X-ray diffraction data has shown that the mean Zn-Br bond length within the zinc (II) bromo complexes shortens gradually with increasing temperature, accompanied with an increase in the interligand Br • • • Br distance. This finding suggests that the Br-Zn-Br bond angle increases with decreasing Zn-Br distance for the lower zinc(II) bromo complexes. The equilibrium shift of the zinc (II) bromo complexes with temperature is discussed on the basis of ion-ion, ion-water, and water-water interactions. 
  Reference    Z. Naturforsch. 47a, 485—492 (1992); received November 27 1991 
  Published    1992 
  Keywords    Raman spectroscopy, X-ray diffraction, Zinc(II)bromide, High temperature, Solution structure 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0485.pdf 
 Identifier    ZNA-1992-47a-0485 
 Volume    47 
3Author    Toshiyuki Takam, KeisukeN. Akam Ura, M. Ikito Ihara, Hisanobu Wakita, Toshio YamaguchiRequires cookie*
 Title    Raman Scattering and X-ray Diffraction Studies on Zinc(II) Bromide Solutions in Methanol and N,N-Dimethylformamide in the Temperature Range 77-333 K  
 Abstract    n Z i n c (I I) B r o m i d e S o l u t i o n s i n M e t h a n o l a n d N , N -D i m e t h y l f o r m a m i d e i n t h e T e m p e r a t u r e R a n g e 7 7 -3 3 3 K The structure o f zinc(II) brom o com plexes in m ethanol and N,N-dim ethylformam ide (D M F) (molar ratio [solvent]/[ZnBr?] = 10, temperature range 7 7 -3 3 3 K) has been investigated by Raman scattering and X-ray diffraction. In the m ethanol solution symmetric Z n -B r vibrations (vt) o f the dibrom o-and tribrom ozinc(II) com plexes were observed at 209 and 184 c m " 1, respectively. With decreasing temperature the intensity o f the vx band decreased for the dibrom o and increased for the tribromo complex. In addition, the Vj band for the tetrabromo complex appeared in the supercooled and glassy methanol solutions. In the D M F solution only one band, assigned to both the dibrom o-and tribromozinc(II) com plexes, was observed. Its intensity did not change with temper­ ature. The X-ray diffraction data revealed that the average number of Z n -B r interactions within the zinc (II) bromo com plexes does not change with temperature while the number of nonbonding Br • • • Br interactions within the com plexes increases from 1.5 at 298 K to 1.9 at 243 K for the methanol solution and from 1.3 at 298 K to 1.8 at 243 K for the D M F solution. These Raman and X-ray results have confirmed that in both m ethanol and D M F solutions at high temperatures the dibrom o species is predominantly formed, whereas at low temperatures the tribromo com plex is favored, the tetrabromo species being formed only in the supercooled and glassy m ethanol solutions. The temperature dependent equilibrium shifts of the zinc(II) bromo complexes in the methanol and D M F solutions are discussed together with previously reported results for the aqueous phase. 
  Reference    Z. Naturforsch. 49a, 1119 (1994); received O ctober 15 1994 
  Published    1994 
  Keywords    Raman spectroscopy, X-ray diffraction, Zinc(II) bromide, M ethanol, N, N -D im ethyl-formamide 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-1119.pdf 
 Identifier    ZNA-1994-49a-1119 
 Volume    49