ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 35, Number 6
JKCSEZ 35(6)
December 20, 1991 

The crystal structure of a bromine sorption complex of dehydrated fully Ca2+-exchanged zeolite A (a = 12.211(2) Å) has been determined by single-crystal X-ray diffraction techniques in the cubic space group, Pm3m at 21(1)℃. The crystal was prepared by dehydration at 360℃ and 2 × 10-6 Torr for 2 days, followed by exposure to about 180 Torr of bromine vapor at 24℃ for 30 min. In the resulting structure, six Ca2+ ions are located on two different threefold axes associated with 6-ring oxygens. A total of six dibromine molecules are sorbed per unit cell. Each Br2 molecule approaches a framework oxide ion axially, with O-Br = 3.12(7) Å, Br-Br = 2.64(9) Å and O-Br-Br = 178(2)°, indicating a charge-transfer interaction. Full-matrix least-squares refinement converged to a conventional R index of 0.104 using the 103 independent reflections for which I > 3σ (I).