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1999 (1)
1995 (1)
1Author    Ingmar Persson, Magnus Sandström, Haruhiko Yokoyama, Monika Chaudhry, JapanRequires cookie*
 Abstract    tr u c tu r e o f th e S o lv a te d S tr o n tiu m a n d B a riu m I o n s in A q u e o u s, D im e th y l S u lfo x id e a n d P y r id in e S o lu tio n , a n d C r y s ta l S tr u c tu r e o f S tr o n tiu m a n d B a r iu m H y d r o x id e O c t a h y d r a te Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday Single crystal X-ray data, collected at 298 K, are used to redetermine the crystal structure of the non-isomorphic compounds [Sr(H20)8](0H)2 and [Ba(H20)8](0H)2. The eight water oxygen atoms form distorted Archimedean antiprisms around the octahydrated metal ions with mean metal ion-oxygen distances 2.62 and 2.79 Ä for strontium and barium, respectively. A second coordination shell of 24 hydrogen-bonded oxygen atoms with mean metal ion-oxygen distances M • • • O" 4.76 and 4.80 A, respectively, is observed. The hydroxide ions in both structures have an unusual hydrogen bond arrangement with 5 bonds accepted and one donated. The structure of the solvated strontium and barium ions in aqueous, dimethyl sulfoxide and pyridine solutions has been studied by means of large angle X-ray scattering and extended X-ray absorption fine structure spectroscopy techniques. In aqueous solution independent determinations of the first-sphere metal-oxygen coordination by the two techniques resulted in the bond lengths Sr-O 2.63 (2) and Ba-O 2.81 (3) A, and for both metal ions a hydration number of 8.1 (3). The second coordination spheres are very diffuse with only about 13 water molecules at similar M • • • O" distances as in the crystal structures and 2-3 water molecules closer to the metal ions. In dimethyl sulfoxide solution both ions were found to coordinate 6.0 (5) solvent molecules with the distances Sr-O 2.54(1), Sr -S 3.77(1) A, and Ba-O 2.76(1), Ba -S 3.99(1) A. For the solvated ions in pyridine solution EXAFS measurements yielded the distances Sr-N 2.57 (2) and Ba-N 2.78 (3) A, with a probable solvation number of 6. Correlations of hydration enthalpies and partial molar volumes with experimental M-O bond distances in aqueous solution are used to discuss hydration numbers and bond character for all of the alkaline earth metal ions. 
  Reference    Z. Naturforsch. 50a, 21—37 (1995); received November 8 1994 
  Published    1995 
  Keywords    Barium, Strontium, Hydration, Solvation, Structure 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0021.pdf 
 Identifier    ZNA-1995-50a-0021 
 Volume    50 
2Author    Masahiko Matsumiya, Masatoshi Takano, Ryuzo Takagi, Reiko FujitaRequires cookie*
 Title    Electrochemical Behavior of Ba 2+ at Liquid Metal Cathodes in Molten Chlorides  
 Abstract    The electrochemcal behavior of Ba 2+ on several liquid metal electrodes (AI, Bi, Cd, Pb, Sn and Zn) in a NaCl-KCl equimolar solvent at 1000 K has been investigated by means of cyclic voltammetry and chronopotentiometry. The kinetic parameters and the diffusion coefficient for Ba 2+ were determined by cyclic voltammetry with conventional, semi-integral, semi-differential methods and chronopotentiometry. It was revealed that on a liquid Pb electrode in the NaCl-KC1 system at 1000 K the quasi-reversible cathodic reaction Ba 2+ + 2e~ + Pb —> BaPb takes place. In addition, the kinetic parameters and the diffusion coefficient agree well with the values determined by various electroanalyses. The possibility of alloy formation between Ba and Sn was also demonstrated in this paper. 
  Reference    Z. Naturforsch. 54a, 739—746 (1999); received September 13 1999 
  Published    1999 
  Keywords    Alloy Formation Reaction, Barium, Liquid Metal Cathodes, Molten Salts 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0739.pdf 
 Identifier    ZNA-1999-54a-0739 
 Volume    54