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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 11, Number 4
BKCSDE 11(4)
April 20, 1990 

Three Crystal Structures of Dehydrated Cd2+ and Rb+ Exchanged Zeolite A, CdxRb12-2x-A, x=4.0, 5.0 and 5.95
Yeong Sim Song, Un Sik Kim, Yang Kim*, Duk Soo Kim
Three crystal structures of dehydrated Cd(Ⅱ) and Rb(Ⅰ) exchanged zeolite A, Cd4.0-Rb4.0-A (a = 12.204(3) Å), Cd5.0Rb2.0-A (a = 12.202(1) Å), and Cd5.95Rb0.1-A (a = 12.250(2) Å), 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 Cd(NO3)2·4H2O and RbNO3 aqueous solution with total concentration of 0.05 M. All crystals were dehydrated at ca. 450℃ and 2×10-6 Torr for 2 days. In all of these structures, Cd2+ ions are found on threefold axes, each nearly at the center of a 6-oxygen ring. The first three Rb+ ions per unit cell preferentially associate with 8-oxygen rings, and additional Rb+ ions, if present, are found on threefold axes in the large cavity. The final R1 and R2 values for the three structures are 0.087 and 0.079, 0.059 and 0.067, and 0.079 and 0.095, respectively.
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