Two crystal structures of dehydrated

exchanged zeolite A,

5-A, reacting with 0.01 Torr of Cs vapor at

for 2 hours and 0.1 Torr of Cs vapor at

for 48 hours, respectively, have been determined by single crystal X-ray diffraction techniques. Their structures were solved and refined in the cubic space group Pm3m at

. The stoichiometry of first crystal was

-A (a = 12.294(1)

), indicating that Cs vapor did not react with cations in zeolite A and that of second crystal was

-A (a = 12.166(1)

), indicating that all

ions were reduced by Cs vapor and replaced by

ions. Full-matrix least-squares refinements of

-A has converged to the final error indices,

= 0.048 with 227 reflections, and

= 0.120 with 167 reflections, respectively, for which I >

(I). In the structure of

-A, both

ions and

ions lie on two crystal symmetrically independent threefold axis sites on the 6-rings;

ions are recessed 0.33

from the (111) planes of three O(3) oxygens and 5

ions lie on the nearly center of each 6-oxygen planes. In the structure of

ions lie on the 5 different crystallographic sites. 3

ions lie at the centers of the 8-rings at sites of D4h symmetry. 6

ions lie on the threefold axes of unit cell:

ions are found deep in the large cavity and 2

ions are found in the sodalite cavity. One

ion is found in the large cavity near a 4-ring.