Yang Kim

Crystal structure of Pb2+44Pb4+5Tl+18O2−17–Si100Al92O384, zeolite X exchanged with Pb2+ and Tl+ and dehydrated, containing Pb4O4(Pb2+,Pb4+mixed)4 clusters

Abstract A single crystal of zeolite X was ion exchanged using a mixed aqueous solution, equinormal in Pb2+ and Tl+, with a total concentration of 0.05xa0M. It was then vacuum dehydrated at 380°C and 2×10−6xa0Torr, and its structure was determined by X-ray diffraction techniques in the cubic space group Fd 3 at 21°C (a=25.119(6)xa0A). The structure, of formula Pb2+44Pb4+5Tl+18O2−17–Si100Al92O384 per unit cell, was refined to the final error indices R1=0.057 and R2=0.055 with 475 reflections for which I>3σ(I). The reaction that occurred upon evacuation at elevated temperature may be written, per unit cell, as 34Pb2++24OH−→4.25[Pb4O4(Pb2+12/17Pb4+5/17)4]176/17++5H2+7H2O. Lead ions occupy three nonequivalent sites. Five lead ions at site II are identified as Pb4+ by their coordination geometry: each is nearly in a six-ring plane where it coordinates to three framework oxygen atoms at 2.23(2)xa0A and also to a nonframework oxygen at 2.11(7)xa0A. There are also 12 Pb2+ ions occupying site II: each is 2.45(2)xa0A from three framework oxygen atoms and 2.78(7)xa0A from a nonframework oxygen. About 53% of the sodalite cages are filled by a Pb4O4(Pb2+,Pb4+mixed)4 cluster whose neutral Pb4O4 core is nearly a cube with Pb2+ and O2− ions alternating. The four Pb2+ ions in the core are at site I′, where each is 2.594(14)xa0A from three framework oxygen atoms and 2.62(6)xa0A from three nonframework oxygen atoms. There are 18 Tl+ ions located at two nonequivalent sites: 15 complete the filling of site II (each is 2.708(14)xa0A from three framework oxygen atoms), and the remaining three are at III′ (each is 2.52(8)xa0A from one framework oxygen and 3.12(9)xa0A from another). Upon dehydration, the zeolite retains only those nonframework oxygen atoms that can be accommodated in Pb8O4n+ clusters.

Crystal structures of fully dehydrated fully Sr2+-exchanged zeolite X and of its ammonia sorption complex

Abstract The crystal structures of fully dehydrated Sr 46 –X [Sr 46 Si 100 Al 92 O 384 ; a =25.214(7)xa0A] and of its ammonia sorption complex, Sr 46 –X·102NH 3 [Sr 46 Si 100 Al 92 O 384 ·102NH 3 ; a =25.127(7)xa0A], have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd 3 at 21(1)°C. The Sr 46 –X crystal was prepared by ion exchange in a flowing stream of aqueous 0.05xa0M Sr(ClO 4 ) 2 for 5xa0days followed by dehydration at 360°C and 2×10 −6 xa0Torr for 2xa0days. To prepare the ammonia sorption complex, another dehydrated Sr 46 –X crystal was exposed to 230xa0Torr of zeolitically dried ammonia gas for 1xa0h followed by evacuation for 12xa0h at 21(1)°C and 5×10 −4 xa0Torr. The structures were refined to the final error indices, R 1 =0.043 and R w =0.039 with 466 reflections, and R 1 =0.049 and R w =0.044 with 382 reflections, for which I >3σ( I ). In dehydrated Sr 46 –X, all Sr 2+ ions are located at two crystallographic sites. 16 Sr 2+ ions are at the centers of the double six-rings, filling that site (site I, Sr–O=2.592(6)xa0A). The remaining 30 Sr 2+ ions are in the supercage (site II); each extends 0.56xa0A into the supercage from the plane of its three nearest oxygen atoms (Sr–O=2.469(6)xa0A). In the structure of Sr 46 –X·102NH 3 , the Sr 2+ ions are located at three crystallographic sites: 12 are found at site I [Sr–O=2.652(10)xa0A]; four in the sodalite units (site I′) each coordinated to three framework oxygen atoms at 2.654(9)xa0A and also to three ammonia molecules at 2.76(8)xa0A. The remaining 30 Sr 2+ ions lie at site II. Each extends 1.12xa0A into the supercage where it coordinates to three framework oxygen atoms at 2.584(7)xa0A and also to three ammonia molecules at 2.774(24)xa0A.

Crystal structure of fully dehydrated fully TI+ -exchanged zeolite X

The structure of TI 92 -X (TI 92 Si 100 Al 92 O 384 ), a = 25.043(1) A, fully dehydrated at 400°C and 1 × 10 −6 torr, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd 3 at 22(1)°C. The structure was refined to the final error indices R = 0.047 and R w = 0.048 with 545 reflections for which l > 3σ( l ). In this structure, 92 TI + ions are located at four different crystallographic sites. Thirty-two fill site l in the sodalite cavities on 3-fold axes opposite double 6-rings; each is 1.44 A from the plane of three oxygens (TI-O = 2.59(1) A, O-TI-O = 92.5(5)°). Another 32 TI + ions fill site II opposite single 6-rings in the supercage; each is 1.56 A from the plane of three oxygens (TI-O = 2.68(1) A and O-TI-O = 89.7(1)°). About 16 TI + ions are found at a III site in the supercage (TI-O = 2.81(2) and 2.87(2) A), and the remaining 12 occupy another III site (TI-O = 2.38(2) and 2.95(4) A).

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

Abstract The structure of Mn46Si100Al92O384xa0·xa089H2S (a=24.628(7) A), 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 at 21(1) °C. A crystal of Mn46-X, dehydrated at 380 °C and 2xa0×xa010−6 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) A). Each of 25 Mn2+ ions at site II extends 0.49 A into the supercage and coordinates to three six-ring oxygens and one H2S molecule deeper in the supercage (Mn–S=2.454(8) A). 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) A). 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) A, respectively, with Mn–S–Mn=94.9(9)°). The Mn2+ ions at site I′ are recessed deeply, 1.40 A into their sodalite cavities from their six-rings to maximize an Mn2+⋯Mn2+ contact, 2.70(3) A, through a six-ring. In contrast, the Mn2+ ions at site II′ are only 0.43 A 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).

MOLECULES OF COPPER(II) l-SPARTEINE DINITRATE ARE MIXED FOUR- AND FIVE-COORDINATE IN ONE CRYSTALLINE PHASE AND ONLY FOUR-COORDINATE IN ANOTHER

Abstract A neutral complex of Cu(II) with the chiral bidentate nitrogen-chelating alkaloid (−)-sparteine, with nitrate groups occupying the remaining coordination sites, has been prepared and characterized. Solution conductivity measurements indicate that both nitrate groups are coordinated to copper to give a neutral molecule. Optical and electron-spin-resonance spectra in toluene/CHCl3, did not show a clear picture of the coordination geometry. A frozen-glass ESR spectrum showed the same evidence for mixed species, with the predominant species characterized by a very low A11 value of 118 G. Crystals 1 and 2 of Cu(C15H26N2)(NO3)2 were grown by two methods: 1 at 25°C from saturated acetonitrile, and 2 at 5°C from ethanol/dichloromethane under CCl4 vapor. Their structures were determined by X-ray crystallography. Crystals 1 were monoclinic, space group P21, with a = 7.851(6), b = 14.408(10), c = 16.079(10) A, β = 97.93(6)°, V = 1801(2) A and Z = 4. Crystals 2 were orthorhombic, space group P212121, with a ...

Crystal structure of an ammonia sorption complex of dehydrated fully Ca2+-exchanged zeolite X

Abstract The structure of an ammonia sorption complex of dehydrated fully Ca 2+ -exchanged zeolite X, Ca 46 Si 100 Al 92 O 384 ·∼135NH 3 ( a =24.904(4)xa0A), has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd 3 at 21(1)°C. The complex was prepared by dehydration of a single crystal of Ca 46 -X at 380°C and 2×10 −6 xa0Torr for 2 days, followed by exposure to 300xa0Torr of ammonia gas at 21(1)°C. The structure was determined in this atmosphere and was refined to the final error indices R 1 =0.074 and R 2 =0.069 with 332 reflections for which I >3 σ ( I ). Ca 2+ ions are located at two crystallographic sites. Sixteen Ca 2+ ions fill the octahedral sites I at the centers of the hexagonal prisms (Ca–O=2.408(8)xa0A). The remaining 30 Ca 2+ ions are at sites II; each extends 0.87xa0A into the supercage (an increase of 0.57xa0A upon NH 3 sorption) where it coordinates octahedrally to three framework oxygens at 2.382(7)xa0A and to three ammonia molecules at 2.75(2)xa0A. Each of the remaining 45(3) NH 3 molecules hydrogen bonds via its lone pair to two coordinating NH 3 molecules and is in position to associate weakly with two or more framework oxygens. To avoid an impossibly short N⋯N contact, this position has a maximum occupancy of 48 per unit cell; it may be full.

Crystal structure of an ethylene sorption complex of fully dehydrated, fully oxidized, fully Ag+-exchanged zeolite X

Abstract The crystal structure of an ethylene sorption complex of fully dehydrated, fully oxidized, fully Ag + -exchanged zeolite X, (Ag + ) 92 Si 100 Al 92 O 384 xa0·xa027C 2 H 4 ( a =24.981(9) A), |Ag 92 (C 2 H 4 ) 27 | [Al 92 Si 100 O 384 ]- FAU , has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd 3 at 21 °C. Ion exchange was accomplished by allowing 0.05 M aqueous AgNO 3 to flow past a crystal for 3 days to give hydrated Ag 92 Si 100 Al 92 O 384 . This crystal was dehydrated at 400 °C for 2 days followed by cooling to 21 °C, both in a flowing stream of zeolitically dry oxygen gas (790 Torr), followed by evacuation at 2xa0×xa010 −6 Torr for 20 min. To prepare the ethylene sorption complex, this colorless crystal was treated at 21 °C with 300 Torr of zeolitically dry ethylene gas for 2 h. The structure of the resulting dark yellow crystal was determined in this atmosphere and was refined to the final error index wR 2 based on F 2 and all data (1155) of 0.293; R 1 =0.069 for the 221 reflections for which F 0 >4σ ( F 0 ). In this structure, per unit cell, 12 Ag + ions were found at the octahedral site I (Ag–O=2.63(2) A) and 16 Ag + ions occupy the nearby site-I ′ positions (Ag–O=2.47(3) A). A significant 2.951-A interaction must occur between the Ag + ions at sites I and I ′ ; linear (Ag 3 ) 3+ is proposed. Thirty-two Ag + ions fill the single 6-rings, 27 at site II (Ag–O=2.41(2) A) and 5 at site II ′ (Ag–O=2.30(4) A). Each of the 27 site-II Ag + ions extends 1.08 A into the supercage to form a strong lateral π-complex with an ethylene molecule. In turn, each C 2 H 4 molecule forms two electrostatic hydrogen bonds to framework oxygens. The remaining 32 Ag + ions occupy four different III ′ sites. The Ag + site occupancies changed substantially upon the sorption of ethylene.

Weak Ag+–Ag+ bonding in zeolite X. Crystal structures of Ag92Si100Al92O384 hydrated and fully dehydrated in flowing oxygen

Abstract Two crystal structures of fully Ag + -exchanged zeolite X, one hydrated ( a =24.996(4) A) and the other fully dehydrated ( a =25.200(4) A), have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd 3 at 21(1)°C. Each initial Na 92 –X crystal was ion exchanged in a flowing stream of 0.05 M aqueous AgNO 3 . The second crystal was dehydrated at 360°C for two days in a flowing stream of oxygen gas (790 Torr) followed by evacuation at 400°C and 2×10 −6 Torr for 2 h. Their structures were refined to the final error indexes R 1 / R 2 =0.088/0.104 with 216 reflections, and R 1 / R 2 =0.047/0.041 with 312 reflections, respectively, for which I >3 σ ( I ). Both structures show weakly attractive 3.0–3.3 A Ag + –Ag + interactions. In the hydrated crystal , 92 Ag + ions were found at seven crystallographic sites: 16 fill site I at the centers of the double six-rings, 16 at site I ′ in the sodalite cavities opposite double six-rings bond weakly (3.045(3) A) to those at site I, 32 fill site II in the supercages, and 28 occupy four different III ′ sites. Some H 2 O molecules were found at two different 3-fold axis sites: 16 coordinate to site I ′ Ag + ions in the sodalite cavities, and 32 coordinate to site II Ag + ions in the supercage. In the dehydrated crystal , Ag ions or atoms were found at eight crystallographic sites: three Ag + ions are at site I, 26 Ag + ions and six Ag 0 atoms are at two I ′ sites in the sodalite cavities filling site I ′ , 32 Ag + ions fill site II as in crystal 1, two Ag 0 atoms are on 2-fold axes in the sodalite cavities, and 23 Ag + ions occupy three different III ′ sites. The 26 Ag + ions at site I ′ bond weakly in pairs (3.224(3) A). Three linear Ag 3 + clusters per unit cell with atoms at sites I ′ , I, and I ′ , respectively, lie along 3-fold axes, and two bent 168(2)° Ag 3 2+ clusters per unit cell are in the sodalite cavities. It remains possible, considering Ag–Ag and Ag–O distances, that no Ag 0 atoms have formed, that the product is (Ag + ) 92 –X, and that the bonding in the clusters, both of which would then be Ag 3 3+ , is due to additional Ag + –Ag + interactions.

Crystal structure of a carbon monoxide sorption complex of dehydrated fully manganese(II)-exchanged zeolite X

Abstract The crystal structure of a carbon monoxide sorption complex of vacuum-dehydrated Mn 2+ -exchanged zeolite X, Mn 46 Si 100 Al 92 O 384 ·30CO ( a =24.715(8)xa0A) has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd 3 at 21(1)°C. The complex was prepared by dehydration at 380°C and 2×10 −6 xa0Torr for 3 days, followed by exposure at 21(1)°C to 270xa0Torr of carbon monoxide gas. The structure was determined in this atmosphere and was refined to the final error indices, R 1 =0.055 and R 2 =0.049 with 321 reflections for which I >3 σ ( I ). Mn 2+ ions are located at two different sites of high occupancy: 16 Mn 2+ ions fill site I at the centers of the double six-rings, and the remaining 30 Mn 2+ ions nearly fill site II in the supercage. Each of these latter Mn 2+ ions is recessed 0.30xa0A into the supercage from the plane of the three oxygens to which it is bound and coordinates linearly via C to a CO molecule [C–O=0.96(3)xa0A] deeper in the supercage. Each site-II Mn 2+ ion is four-coordinate, to three framework oxygens and to one molecule of CO [Mn–C=2.57(3)xa0A, Mn–O=2.130(9)xa0A, O–Mn–O=118.1(5)° and O–Mn–C=98.0(3)°]. The Mn–C bond length is somewhat long, indicative of a relatively weak Mn–CO electrostatic interaction.

Crystal structure of a hydrogen sulfide sorption complex of zeolite LTA

3 ¯ m at 21(1) °C. The structure was refined to the final error indices R = 0.047 and Rw = 0.033 with 153 reflections for which I > 3σ(I). Twelve H2S molecules are sorbed per unit cell. Eight Na+ ions are found at two different 6-oxygen-ring sites, where each coordinates to three framework oxygens at ca. 2.32(2) A. Six of the eight Na+ ions extend 0.47(1) A into the large cavity from the (111) planes of the 6 rings, where each coordinates at 2.98(2) A to one H2S sulfur in the large cavity. The remaining two 6 ring Na+ ions do not associate with H2S and are located near the centers of their 6 rings. Three Na+ ions are found in 8-oxygen-ring planes, where each coordinates to one framework oxygen at 2.39(2) A and to two H2S sulfurs in the large cavities at 2.74(3) A. The twelfth Na+ ion coordinates to the four framework oxygens of a 4-ring at 2.71 (3) A, and to one or two of the above H2S molecules at 2.78(6) A. The sodalite cavities are empty.