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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 11, Number 2
BKCSDE 11(2)
February 20, 1990 

Two Crystal Structures of Tl+ and Zn2+ Exchanged Zeolite A, Tl12-2xZnx-A (x=4.3 and 3.25)
Mi Suk Jeong, Seong Hwan Song, Young Wook Han, Yang Kim*
The structures of Tl12-2xZnx-A (x = 4.3 and 3.25), vacuum dehydrated zeolite A with all Na+ ions replaced by Tl+ and Zn2+ as indicated, have been determined by single-crystal X-ray diffraction techniques in cubic space group Pm3m at 21(1) ℃ (a = 12.100(2) Å for Tl3.4Zn4.3-A and a = 12.092(2) Å for Tl5.5Zn3.25-A). The crystals of Tl3.4Zn4.3-A and Tl5.5Zn3.25-A were prepared by flow method using exchange solutions in which mole ratios of TlNO3 and Zn(NO3)2 were 1:50 and 1:1, respectively, with total concentration of 0.05 M. The structures of the dehydrated Tl3.4Zn4.3-A and Tl5.5Zn3.25-A were refined to yield the final error indices R1 = 0.075 and R2 = 0.075 with 236 reflections, and R1 = 0.057 and R2 = 0.064 with 202 reflections, respectively, for which I > 3σ(Ⅰ). Both structures indicate that Zn(Ⅱ) ions are coordinated by three framework oxygens: the Zn(Ⅱ) to O(3) distances are 2.08(1) Å for Tl3.4Zn4.3-A and 2.07(1) Å for Tl5.5Zn3.25-A, respectively. In each structure, the angle subtended at Zn(Ⅱ), O(3)-Zn(Ⅱ)-O(3) is 119.9(3)° for Tl3.4Zn4.3-A, and 120.0(3)° for Tl5.5Zn3.25-A, respectively, close to the idealized trigonal-planar value. Zn(Ⅱ) ions prefer to 6-ring sites. Tl+ ions do not have any preference to a particular site but occupy simultaneously both at the 6-ring sites and 8-ring sites.
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