Crystal structure of Mn46Si100Al92O384 • 89H2S, a hydrogen sulfide sorption complex of fully dehydrated Mn2+-exchanged zeolite X

The structure of Mn46Si100Al92O384.89H(2)S (a = 24.628(7) Angstrom), 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 Fd (3) over bar at 21(l) degreesC. A crystal of Mn-46-X, dehydrated at 380 degreesC and 2 x 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 > 3sigma(I) are R-1 = 0.065 and R-2 = 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 Mn-46-X. Sixteen Mn2+ ions fill site 1, at the centers of the double six-rings (Mn(octahedral)-O = 2.285(9) Angstrom). Each of 25 Mn2+ ions at site II extends 0.49 Angstrom into the supercage and coordinates to three six-ring oxygens and one H2S molecule deeper in the supercage (Mn-S = 2.454(8) Angstrom). 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) Angstrom). Altogether 81 H2S molecules are sorbed in the eight supercages per unit cell. Of the eight socialite cavities, 2.5 have a Mn2+ ion at site F, another at site IF, and a sulfur atom (likely HS-) bridging between them (Mn-S = 2.49(2) and 2.43(3) Angstrom, respectively, with Mn-S-Mn = 94.9(9)degrees). The Mn2+ ions at site F are recessed deeply, 1.40 A into their sodalite cavities from their six-rings to maximize an Mn2+...Mn2+ contact, 2.70(3) Angstrom, through a six-ring. In contrast, the Mn2+ ions at site II' are only 0.43 Angstrom 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) A). (C) 2003 Elsevier Inc. All rights reserved.