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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 14, Number 2
BKCSDE 14(2)
February 20, 1993 

Two Crystal Structures of Dehydrated Fully Ca2+-Exchanged Zeolte A Reacting with Rubidium Vapor
Seong Hwan Song, Yang Kim*
Two single crystals of fully dehydrated Rb+-exchanged zeolite A have been prepared by the reduction of all Ca2+ ions in dehydrated Ca6-A by rubidium vapor. Their structures were determined by single crystal X-ray diffraction methods in the cubic space group Pm3m (a=12.160(2) Å and 12.166(2) Å) at 22(1)℃. In these structures, 12.4(2) to 13.3(2) Rb species are found per unit cell, more than 12 Rb+ ions needed to balance the anionic charge of the zeolite framework, indicating that the sorption Rb0 has occurred. In each structure, three Rb+ ions per unit cell are located at the centers of the 8-rings. Six to eight Rb+ ions are found opposite the 6-rings on threefold axes, and three Rb+ ions are found in a sodalite unit. About 0.5 Rb+ ion lies opposite a 4-ring. The structural analysis indicates the presence of a triangular rubidium cluster in the sodalite cavities. The triangular rubidium clusters may be stabilized by the coordination to two and/or three rubidium ions in the large cavity. Therefore, this cluster may be viewed as (Rb5)4+ and/or (Rb6)4+.
258 - 262
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