Crystal structure of Mn46Si100Al92O384·89H2S, a hydrogen sulfide sorption complex of fully dehydrated Mn2+-exchanged zeolite X
Microporous and Mesoporous Materials(2003)
摘要
The structure of Mn46Si100Al92O384·89H2S (a=24.628(7) Å), a hydrogen sulfide sorption complex of fully dehydrated, fully Mn2+-exchanged zeolite X, has been determined by single-crystal X-ray diffraction methods in the cubic space group Fd3 at 21(1) °C. A crystal of Mn46-X, dehydrated at 380 °C and 2×10−6 Torr for 2 days, was treated with 300 Torr of zeolitically dry H2S(g) at ambient temperature, and its structure was determined in this atmosphere. The final error indices for the 217 reflections for which I>3σ(I) are R1=0.065 and R2=0.055. In the final refinement, the 645 reflections with I>0 were used. Mn2+ ions occupy four crystallographic sites, two more than in empty Mn46-X. Sixteen Mn2+ ions fill site I, at the centers of the double six-rings (Mn(octahedral)–O=2.285(9) Å). Each of 25 Mn2+ ions at site II extends 0.49 Å into the supercage and coordinates to three six-ring oxygens and one H2S molecule deeper in the supercage (Mn–S=2.454(8) Å). Fifty-six H2S molecules are found at two III′ sites where each ‘hydrogen bonds’ to two framework oxygens (S–O=3.51(4)/3.50(4) and 3.46(4)/3.52(3) Å). Altogether 81 H2S molecules are sorbed in the eight supercages per unit cell. Of the eight sodalite cavities, 2.5 have a Mn2+ ion at site I′, another at site II′, and a sulfur atom (likely HS−) bridging between them (Mn–S=2.49(2) and 2.43(3) Å, respectively, with Mn–S–Mn=94.9(9)°). The Mn2+ ions at site I′ are recessed deeply, 1.40 Å into their sodalite cavities from their six-rings to maximize an Mn2+⋯Mn2+ contact, 2.70(3) Å, through a six-ring. In contrast, the Mn2+ ions at site II′ are only 0.43 Å from their planes. The remaining 5.5 sodalite cavities each hold an H2S molecule or an H3S+ ion that associates only with framework oxygen atoms by ‘hydrogen bonding’ (S–O=3.551(11) Å).
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关键词
Hydrogen sulfide,Manganese,Zeolite X,Structure,Sorption,Complex
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