The II-VI compounds, those between the elements of Group II (Zn, Cd, and Hg) and Group VI (O, S, Se, and Te), have characteristic semiconducting properties. Zeolites, because their dehydrated structures have voids, have been widely studied as hosts for quantum dots of semiconductors. The structures of the sub-nanometer clusters of CdS that form in zeolite Y (FAU), prepared as follows, have been determined. A single crystal of Cd2+-exchanged zeolite Y was prepared by the exchange of Na75-Y (|Na75|[Si117Al75O384]-Y with aqueous Cd(NO3)2 at 294 K, followed by vacuum dehydration at 723 K (crystal 1). A second crystal, similarly prepared, was exposed to 6.7 × 104 Pa of dry H2S(g) for six hours at 294 K and evacuated (crystal 2). Their structures were determined crystallographically using synchrotron X-rays and were refined using all data to the final error indices (calculated using only Fo &gt; 4s(Fo)) of R1/wR2 = 0.040/0.156 and 0.049/0.186, respectively. In crystal 1, Cd2+ ions primarily occupy sites I and II. In crystal 2, |Cd27(Cd4S6+)0.6(Cd(SHCd)46+)0.9H12|[Si117Al75O384]-FAU, tetrahedral Cd4S6+ ions center about 7.5% of the sodalite cavities and tetrahedral Cd(SHCd)46+ ions center about 11% of the supercages. In Cd(SHCd)46+, a Cd2+ ion at the center of a supercage bonds tetrahedrally to four SH- ions, each of which bonds in turn to a 6-ring Cd2+ ion. Of the 36.5(9) Cd2+ ions per unit cell (indicating complete or nearly complete Cd2+ exchange) before treatment with H2S(g), only 6.9 participate in the above clusters. Most, 27, remain uncomplexed, and 2.6 have left the zeolite as CdS(s). No neutral clusters of formula CdnSn are present within the zeolite.

Crystal Structures of fully dehydrated fully Cd2+-exchanged zeolite Y (FAU) and of its H2S sorption complex containing the cationic cadmium sulfide clusters Cd4S6+ and Cd(SHCd)46+

254th National Meeting (2017)

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