Three single crystals of excessively Cd2+-exchanged zeolite Y were prepared by the exchange of Na-Y (vertical bar Na-75 vertical bar[Si117Al75O384]-FAU, Si/Al = 1.56) with an aqueous stream 0.25 M each in Cd(NO3)(2) and Cd(C2H3O2)(2) at 294 K (crystals 1 and 2) and 353 K (crystal 3), followed by vacuum dehydration at 1 x 10(-6) Torr and 423 K (crystal 1) and 723 K (crystals 2 and 3). Their crystal structures were determined by diffraction experiment using synchrotron X-radiation in the cubic space group Fd (3) over barm. They were refined to the final error indices R-1/wR(2) = 0.0502/0.1445, 0.0702/0.1960, and 0.0643/0.1747 for crystals 1, 2, and 3, respectively. The number of Cd2+, H2O, OH-, and O2- ions or molecules in the three crystal structures are about 43.5, 23, 12, 0; 43.5, 0, 0, 6; and 47.5, 0, 0, 10 per unit cell for crystals 1, 2, and 3, respectively. In all cases, over-exchange due to uptake of OH- occurred. Crystals 1 and 2 had imbibed about 6 Cd(OH)(2) molecules per unit cell, perhaps as CdOH+ ions, crystal 3 ten, indicating this increase in imbibition as temperature increased from 294 K to 353 K. These decomposed upon vacuum dehydration at 723 K to give, with additional Cd2+ ions, Cd8O48+ clusters (symmetry (4) over bar 3m(T-d)) in the sodalite cavities of crystals 2 and 3. The crystal compositions are vertical bar Cd-8.5(CdOH)(12)(CdOH2)(23)vertical bar[Si117Al75O384]-FAU (crystal 1), vertical bar Cd-31.5(Cd8O4)(1.5)vertical bar[Si117Al75O384]-FAU (crystal 2), and vertical bar Cd-27.5(Cd8O4)(2.5)vertical bar[Si117Al75O384]-FAU (crystal 3), respectively. (C) 2012 Elsevier B. V. All rights reserved.