Silver Hydro Sodalite [Ag3(H2O)4]2[Al3Si3O12]2: Synthesis and Structure Determination by Combination of X-ray Rietveld Refinement, Thermogravimetry, FT-IR, and1H-MAS NMR Spectroscopy

Abstract

Sodium hydro sodalite [Na3(H2O)4]2[Al3Si3O12]2 was subjected to ion exchange with aqueous AgNO3 solutions to yield silver hydro sodalite [Ag3(H2O)4]2[Al3Si3O12]2. A Rietveld structure refinement of the silver hydro sodalite structure based on powder X‐ray diffraction data recorded at room temperature (cubic, a = 8.950 Å, space group P‐43n) led to a model where three silver cations form a triangle nearly parallel to a four‐membered ring of the sodalite cage. In combination with the four water molecules, a disorder model [Ag3(μ‐H2O)2(H2O)2]3+ is suggested. This structural arrangement is clearly different from that found in sodium hydro sodalite. Whereas the sodium hydro sodalite structure is dominated by cation−water interactions, the silver hydro sodalite structure reflects strong interactions between the cations and the oxygen atoms of the framework, strong interactions between the water molecules, but only weak ones between the cations and water molecules. In addition, weak Ag+···Ag+ interactions may play a role. 1H MAS NMR spectra show that the hydrogen atoms (which were not found in the Rietveld analysis) of the water molecules are involved in hydrogen bonding of different strengths and dynamics.

Well-Defined Silanols in the Structure of the Calcined High-Silica Zeolite SSZ-70: New Understanding of a Successful Catalytic Material

“…For the determination of the structures of complex polycrystalline materials, conventional methods are rarely sufficient, so information from different sources must be combined. − This process is much like solving a puzzle, where data and constraints over multiple length scales must be analyzed to establish a structure (or distribution of structures) that is consistent with all data. Sometimes such data simply provides independently corroborative information, but for SSZ-70, the HRTEM images, synchrotron XRPD data, and DNP-enhanced 2D NMR spectra, each provided crucial and complementary insights.…”

Gallium substitution in the alumosilicate framework: synthesis and structural studies of hydro sodalites

“…On the other hand, the reversible dehydration/hydration phenomena and the consequent anomalous effect on framework geometry are only known from hydro sodalites [7,11,12]. Although very many hydro sodalites have been reported within a vast range of chemical compositions, their compositional variations were mostly confined to either topotactic manipulation of the guest species or complete replacement of the framework T-atoms [7,[11][12][13][14][15][16][17][18]. In contrast, partial T-sites substitution in the sodalite frameworks [19][20][21][22] remains little explored whereas extensive commercial successes have been achieved through partial T-sites substitution in zeolites [23,24].…”

Fast Dynamic Exchange between Na+OH– Ion Pairs and H2O Molecules in Sodalites

“…In comparison with the previously described ion exchange/ leaching processes using sodalite matrices where amorphization and/or dramatic reduction of average crystal size were common phenomena [2,3], we applied an open beaker method and checked some intermediate phases formed during the Na + OH -/H 2 O exchanges, which is~12 times faster than autoclave exchange method [1][2][3], and~60 times faster than Soxhlet extraction [4,5]. Moreover, it is simple, non-destructive, and seems to be cheaper.…”

“…Hydro sodalites Na 6 [T 1 T 2 O 4 ] 6 (H 2 O) 8 (T 1 = Al, Ga; T 2 = Si, Ge) [1][2][3][4][5][6][7] are synthetic analogues to the mineral sodalite [8][9][10] and offer typical zeolitic ion-exchange in aqueous solution. They are unique mainly from two standpoints: (I) they do not enclathrate anionic guest species such as Cl -, OH -, NO 2 but neutral H 2 O molecules and, (II) reversible dehydration/hydration phenomena and the consequent anomalous effect on the framework structure are only known from hydro sodalites [1][2][3].…”

“…halide sodalites [11]), in particular, when gallosilicate [6] or alumogallosilicate [7] frameworks are concerned. Therefore, it has been a common practice to produce hydro sodalites from their hydro-hydroxy Na 6+x [T 1 T 2 O 4 ] 6 (OH) x (H 2 O) 8-4x phases (0 < x < 2) either by ion-exchange in Teflon-coated steel autoclaves [1][2][3] or by Soxhlet extraction [4,5] 8 sodalite using the autoclave procedure at 473 K and autogenous pressure [7], however, such transformation should not be considered as ionexchange. Instead, it was demonstrated to be a recrystallization process [7] since the large iodide anion (206 pm [12]) could not leach through the effective six-ring windows (~190 pm) without destroying the β-cages (also known as 'toc' or 'sod' as modern designation [13]).…”