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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 9, Number 5
BKCSDE 9(5)
May 20, 1988 

 
Title
Four Crystal Sturctures of Dehydrated Ag+ and Tl+ Exchanged Zeolite A, Ag12-xTlx-A, x = 2, 3, 4, and 5
Author
Duk Soo Kim, Seong Hwan Song*, Yang Kim*
Keywords
Abstract
Four crystal structures of dehydrated Ag(Ⅰ) and Tl(Ⅰ) exchanged zeolite A, Ag12-xTlx-A, x = 2, 3, 4, and 5, have been determined by single-crystal x-ray diffraction techniques. Their structures were solved and refined in the cubic space group Pm3m at 21(1) ℃. All crystals were ion exchanged in flowing streams of mixed AgNO3 and TlNO3 aqueous solution, followed by dehydration at 350℃ and 2×10-6 Torr for 2 days. In all of these structures, one-sixth of the sodalite units contain octahedral hexasilver clusters at their centers and eight Ag+ ions are found on threefold axes, each nearly at the center of a 6-oxygen ring. The hexasilver cluster is stabilized by coordination to eight Ag+ ions. The Ag-Ag distance in the cluster, ca. 2.92 Å, is near the 2.89 Å bond length in silver metal. The remaining five-sixths of the sodalite units are empty of silver species. The first three Tl+ ions per unit cell preferentially associate with 8-oxygen rings, and additional Tl+ ions, if present, are found on threefold axes in the large cavity.
Page
303 - 308
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