Crystal structure of anhydrous NH{sub 4}{sup +}-exchanged zeolite X partially reacted with HgCl{sub 2} vapor. Cationic chloromercuric clusters, regular octahedral Hg(II), and regular trigonal Hg(II)
The product of the reaction of HgCl{sub 2} vapor with fully dehydrated fully NH{sub 4}{sup +}-exchanged zeolite X at 115 C, ca. Hg{sub 44}Cl{sub 64}(NH{sub 4}){sub 68}-Si{sub 100}Al{sub 92}O{sub 384} per unit cell, was studied by single-crystal X-ray diffraction techniques at 23 C (R{sub 1} = 0.121) in the cubic space group Fd{bar 3} (a{sub 0} = 25.094(8) {angstrom}). Hg{sup 2+} ions are found at seven nonequivalent sites, a surprisingly large number. Hg{sup 2+} ions at sites I and II each coordinate only to framework oxygens; this is the first observation of Hg{sup 2+} ions at conventional ionic sites in a zeolite, and of very nearly regular octahedral Hg(II), and of three-coordinate trigonal Hg(II). Hg{sup 2+} ions at two general site III{prime} positions form (HgCl{sub 2}){sub 3}(NH{sub 4}{sup +}){sub 2} and (HgCl{sub 2}){sub 3}(NH{sub 4}{sup +}) clusters, respectively, in 12-rings with each Hg{sup 2+} ion bonding to one framework oxygen. The Hg{sup 2+} ions at another two general site III{prime} positions form (HgCl{sub 2}){sub 6}(NH{sub 4}{sup +}){sub 2} clusters, also in 12-rings with each Hg{sup 2+} ion bonding to two framework oxygens. These two clusters could bridge through Cl{sup {minus}} ions to form a supercluster that contains as alternative subunits Hg{sub 12}Cl{sub 12} rings each of which wraps around a double six-ring. Site II is full with two Hg{sup 2+} and 30 NH{sub 4}{sup +} ions. In each sodalite cage, an NH{sub 4}{sup +} ion at site I{prime} bonds to three framework oxygens. Two Hg{sup 2+} ions per unit cell are seen near supercage centers; each coordinates to three Cl{sup {minus}} ions that bridge to other Hg{sup 2+} ions. The desired reaction of NH{sub 4}-X with HgCl{sub 2} vapor did not go to completion. Substantial amounts of HgCl{sub 2} were sorbed and cationic superclusters of Hg(II) and Cl{sup {minus}} have formed. This is the first observation of cationic halomercuric species.
- Research Organization:
- Univ. of Hawaii, Honolulu, HI (US)
- OSTI ID:
- 20013646
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Vol. 103, Issue 47; Other Information: PBD: 25 Nov 1999; ISSN 1089-5647
- Country of Publication:
- United States
- Language:
- English
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