Synthesis and single-crystal structure of sodium sulfide cationic cluster in the sodalite cavity of zeolite Y (FAU, Si/Al = 1.56)

The extraframework sodium sulfide cationic cluster, Na 4 S 2+ , has been introduced into zeolite Y (FAU, Si/Al = 1.56). A single crystal of |Na 73 (Na 4 S 2+ ) 1.0 |[Si 117 Al 75 O 384 ]-FAU was prepared by allowing aqueous 0.1 M Na 2 S solution to flow past a |Na 75 |[Si 117 Al 75 O 384 ]-FAU crystal, and followed by vacuum dehydration at 723 K. Its structure was determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd 3 ¯ m . The structure was refined using all intensities to the final error index R 1 / wR 2 = 0.044/0.125. About 77 Na + ions per unit cell are found at the crystallographically distinct positions, six. One Na + ion per unit cell is at the center of double 6-ring. Two site-I′ positions are occupied by 26.5 and 4 Na + ions, respectively, per unit cell. Thirty-two Na + ions per unit cell are found at site II, in the supercage opposite single 6-rings. The remaining 4.5 and 9 Na + ions per unit cell occupy two sites III′ near triple 4-rings in the supercage. Finally, one sulfide ion per unit cell, associated with Na + ions, is found at the center of sodalite cavity. The 4 Na + ions at site I′ coordinate to a sulfide ion at the center of sodalite cavity to give tetrahedral cationic cluster, Na 4 S 2+ . In |Na 73 (Na 4 S 2+ ) 1.0 |[Si 117 Al 75 O 384 ]-FAU, tetrahedral Na 4 S 2+ ions center about 12.5% of the sodalite cavities.