Silver hydro sodalite [Ag-3(H2O)(4)](2)[Al3Si3O12](2): Synthesis and structure determination by combination of X-ray Rietveld refinement, thermogravimetry, FT-IR, and H-1-MAS NMR spectroscopy

Sodium hydro sodalite [Na-3(H2O)(4)](2)[Al3Si3O12](2) was subjected to ion exchange with aqueous AgNO3 solutions to yield silver hydro sodalite [Ag-3( H2O)(4)](2)[Al3Si3O12](2) A Rietveld structure refinement of the silver hyd ro sodalite structure based on powder X-ray diffraction data recorded at ro om temperature (cubic, a = 8.950 Angstrom, space group P-43n) led to a mode l where three silver cations form a triangle nearly parallel to a four-memb ered ring of the sodalite cage. In combination with the four water molecule s, a disorder model [Ag-3(mu -H2O)(2)(H2O)(2)](3+) is suggested, This struc tural arrangement is clearly different from that found in sodium hydro soda lite. Whereas the sodium hydro sodalite structure is dominated by cation-wa ter interactions, the silver hydro sodalite structure reflects strong inter actions between the cations and the oxygen atoms of the framework, strong i nteractions between the water molecules, but only weak ones between the cat ions and water molecules. In addition, weak Ag+... Ag+ interactions may pla y a role. H-1 MAS NMR spectra show that the hydrogen atoms (which were not found in the Rietveld analysis) of the water molecules are involved in hydr ogen bonding of different strengths and dynamics.