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The crystal structures of Cd6-A evacuated at 2 × l0-6 torr and 750℃ (a = 12.204(1) Å) and dehydrated Cd6-A reacted with 0.l torr of Cs vapor at 250℃ for 12 hours (a = 12.279(1) Å) have been determined by single crystal X-ray diffraction techniques in the cubic space group Pm3m at 21(1)℃. Their structures were refined to final error indices, R1 = 0.081 and R2 = 0.091 with 151 reflections and R1 = 0.095 and R2 = 0.089 with 82 reflections, respectively, for which I > 3σ(I). In vacuum dehydrated Cd6-A, six Cd2+ ions occupy threefold-axis positions near 6-ring, recessed 0.460(3) Å into the sodalite cavity from the (111) plane at O(3) : Cd-O(3) = 2.18(2) Å and O(3)-Cd-O(3) = 115.7(4)°. Upon treating it with 0.1 torr of Cs vapor at 250℃, all 6 Cd2+ ions in dehydrated Cd6-A are reduced by Cs vapor and Cs species are found at 4 crystallographic sites : 3.0 Cs+ ions lie at the centers of the 8-rings at sites of D4h symmetry; ca. 9.0 Cs+ ions lie on the threefold axes of unit cell, ca. 7 in the large cavity and ca. 2 in the sodalite cavity; ca. 0.5 Cs+ ion is found near a 4-ring. In this structure, ca. 12.5 Cs species are found per unit cell, more than the twelve Cs+ ions needed to balance the anionic charge of zeolite framework, indicating that sorption of Cs0 has occurred. The occupancies observed are simply explained by two unit cell arrangements, Cs12-A and Cs13-A. About 50% of unit cells may have two Cs+ ions in sodalite unit near opposite 6-rings, six in the large cavity near 6-ring and one in the large cavity near a 4-ring. The remaining 50% of unit cells may have two Cs species in the sodalite unit which are closely associated with two out of 8 Cs+ ions in the large cavity to form linear (Cs4)3+ clusters. These clusters lie on threefold axes and extend through the centers of sodalite units. In all unit cells, three Cs+ ions fill equipoints of symmetry D4h at the centers of 8-rings.
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