Crystal Structure of Anhydrous NH4+-Exchanged Zeolite X Partially Reacted with HgCl2 Vapor. Cationic Chloromercuric Clusters, Regular Octahedral Hg(II), and Regular Trigonal Hg(II)

The product of the reaction of HgCl 2 vapor with fully dehydrated fully NH 4 + -exchanged zeolite X at 115 °C, ca. Hg 44 Cl 64 (NH 4 ) 68 −Si 100 Al 92 O 384 per unit cell, was studied by single-crystal X-ray diffraction techniques at 23 °C ( R 1 = 0.121) in the cubic space group Fd 3̄ ( a 0 = 25.094(8) Å). Hg 2+ ions are found at seven nonequivalent sites, a surprisingly large number. Hg 2+ ions at sites I and II each coordinate only to framework oxygens; this is the first observation of Hg 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 2+ ions at two general site III‘ positions form (HgCl 2 ) 3 (NH 4 + ) 2 and (HgCl 2 ) 3 (NH 4 + ) clusters, respectively, in 12-rings with each Hg 2+ ion bonding to one framework oxygen. The Hg 2+ ions at another two general site III‘ positions form (HgCl 2 ) 6 (NH 4 + ) 2 clusters, also in 12-rings with each Hg 2+ ion bonding to two framework oxygens. These two clusters could bridge through Cl - ions to form a supercluster that contains as alternative subunits Hg 12 Cl 12 rings each of which wraps around a double six-ring. Site II is full with two Hg 2+ and 30 NH 4 + ions. In each sodalite cage, an NH 4 + ion at site I‘ bonds to three framework oxygens. Two Hg 2+ ions per unit cell are seen near supercage centers; each coordinates to three Cl - ions that bridge to other Hg 2+ ions. The desired reaction of NH 4 -X with HgCl 2 vapor did not go to completion. Substantial amounts of HgCl 2 were sorbed and cationic superclusters of Hg(II) and Cl - have formed. This is the first observation of cationic halomercuric species.