Crystal Structures of Dehydrated Ag+ and Ca2+ Exchanged Zeolite A, Ag3.3Ca4.35-A and of Its Ethylene Sorption Complex

摘要

Two crystal structures of dehydrated Ag3.3Ca4.35-A (メ = 12.256(2) ∈) and of its ethylene sorption complex (メ = 12.259(2) ∈) have been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3m at 21(l)∩. Both crystals were dehydrated at 360∩ and 2】lO-6 Torr for 2 days and one crystal was treated with 200 Torr of ethylene at 24(2)∩. The structures were refined to final error indices, R1=O.065 and R2 = 0.088 with 202 reflections and R1=0.049 and R2 = 0.044 with 259 reflections, respectively, for which I>3ヲ(I). In these structures, all Ag+ and Ca2+ ions are located on two and three different threefold axes associated with 6-ring oxygens, respectively. In Ag3.3Ca4.35-A·6.65 C2H4, 3.3 Ag+ and 3.35 Ca2+ ions are recessed 1.09 ∈ and 0.21 ∈, respectively, into the large cavity from the (111) plane at O(3). Each Ag+ and Ca2+ ion in the large cavity forms a complex with one C2H4 molecule. Distances between Ca2+ ions and ethylene molecules are longer than those between Ag+ ions and ethylene molecules.