Facile synthesis of sub-nanometer Cd4S6+ and Cd2S2+ cluster in zeolite Y and its structural characterization

The Cd 4 S 6+ and Cd 2 S 2+ clusters in the sodalite cavities were synthesized by reaction of the fully Cd 2+ -exchanged zeolite Y (Si/Al = 1.56) and 0.1 M Na 2 S( aq ) solution at 294 K for 2 days. The single-crystal structure was determined at 100(1) K by 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 = 0.048/0.156 (for F o > 4σ( F o )). Approximately 13 Cd 2+ and 53 Na + ions per unit cell were found at two and four crystallographically distinct positions, respectively: two site-Iʹ positions (in the sodalite cavities opposite double 6-rings (D6Rs)) are occupied by 5 and 7.5 Cd 2+ ions, respectively, per unit cell. The 0.5 Cd 2+ ions per unit cell are at site IIʹ in the sodalite cavity. The 2 Na + ion is located at the center of the D6R (site I). The 15.5 Na + ions per unit cell are located at site Iʹ. Site-II position is occupied by 31.5 Na + ions per unit cell. The remaining 4 Na + ions per unit cell are located at sites IIIʹ near triple 4-rings in the supercage. Finally, 0.5 and 1.5 S 2− ions per unit cell, associated with Cd 2+ ions, were found at the center of sodalite cavity and opposite 6-ring in the sodalite cavity, respectively. The 1 S 2− ion at the center of the sodalite cavity is coordinated to 4 Cd 2+ ions at site Iʹ to give a centered-tetrahedral cationic cluster, Cd 4 S 6+ , and the other S 2− ion opposite 6-ring in the sodalite cavity bridges between two Cd 2+ ions at site Iʹ to give a cationic cluster with a bent arrangement, Cd 2 S 2+ , in 6.3% and 18.8% of the sodalite cavities of zeolite Y (Si/Al = 1.56), respectively.