Lead hydro sodalite [Pb-2(OH)(H2O)(3)](2)[Al3Si3O12](2): Synthesis and structure determination by combining X-ray Rietveld refinement, H-1 MAS NMR FTIR and XANES spectroscopy

Ion exchange of the sodium hydro sodalites [Na-3(H2O)(4)](2)-[Al3Si3O12](2) , [Na-4(H3O2)](2)[Al3Si3O12](2) and [Na-4(OH)](2),[Al3Si3O12](2) with aqueo us Pb(NO,I), solutions yielded, whichever reactant sodalite phase was used, the same lead hydro sodalite, [Pb-2(OH)-(H2O)(3)](2)[Al3Si3O12](2) Thus, i n the case of the non-basic reactant [Na-3(H2O)(4)](2)-[Al3Si3O12](2) an ov erexchange occurs with respect to the number of non-framework cationic char ges. Rietveld structure refinement of the lead hydro sodalite based on powd er X-ray diffraction data (cubic. a = 9.070 Angstrom. room temperature. spa ce group <P(4)over bar 3n>) revealed that the two lead cations within each polyhedral sodalite cage form an orientationally disordered dinuclear [Pb-2 (mu-OH)(mu-H2O)(H2O)(2)](3+) complex. Due to additional lead framework oxyg en bonds the coordination environment of each metal cation (CN 3+3) is appr oximately spherical, and clearly the lead 6s election lone pair is sterioch emically inactive. This is also suggested by the absence of a small peak at 13.025 keV, attributed in other Pb2+ - O compounds to an electronic 2p-6s transition, in the PbL3 edge,XANES spectrum. IH MAS NMR and FTIR spectra sh ow that the hydrogen atoms of the aqua hydroxo complex (which could not be determined in the Rietveld analysis) are involved in hydrogen bonds of vari ous strengths.