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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 20, Number 7
BKCSDE 20(7)
July 20, 1999 

 
Title
Crystal Structure of a Cyclopropane Sorption Complex of Dehydrated Fully Ca2+-Exchanged Zeolite X
Author
Eun Young Choi, Yang Kim, Seong Hwan Song
Keywords
Abstract
The crystal structure of a cyclopropane sorption complex of dehydrated fully Ca (2+) -exchanged zeolite X, Ca46Si100Al92O384· 30C3H6 (a = 24.988(4) Å), has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1)℃. The crystal was prepared by ion exchange in a flowing stream of 0.05M aqueous Ca(NO3)2 for four days, followed by dehydration at 460℃ and 2×10 (-6) Torr for two days, and exposure to 100 Torr of cyclopropane gas at 21(1)℃. The structure was determined in this atmosphere and refined to the final error indices R1 = 0.068 and R2 = 0.082, with 373 reflections for which I > 3σ (I). In this structure, Ca 2+ ions are located at two crystallographic sites. Sixteen Ca 2+ ions fill the octahedral sites I at the centers of the hexagonal prisms (Ca-O = 2.412(9)Å). The remaining 30 Ca 2+ ions are at sites Ⅱ; each extends 0.46Å into the supercage (an increase of 0.16Å upon C3H6 sorption) where it coordinates to three trigonally arranged framework oxygens at 2.311(8)Å. Each of the 30 cyclopropane molecules was found to complex to Ca 2+ ions at site II by the induced dipole interaction (Ca-C = 2.99(4)Å). All carbon atoms in each cyclopropane molecule are equivalent and equidistant from Ca 2+ ions at site II with which they are associated.
Page
791 - 795
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