Tetrahydroxytetraindium(III) Nanoclusters, In4(OH)48+, in Air-Oxidized Fully In-Exchanged Zeolite Y (FAU, Si/Al=1.69). Preparation and Crystal Structures of In-Y and In-Y[In4(OH)4]

The polyatomic tetrahydroxytetraindium(III) cations, In-4(OH)(4)(8+), have been synthesized in 94% of the sodalite cavities of zeolite Y (FAU, Si/Al = 1.69). In-Y ([In-57.8[In-5](1,8)I[Si121Al71O384]-FAU or In-66.8-Y) was prepared by the oxidative solid state ion exchange (OSSIE) method from In and single crystals of TI-Y under anhydrous conditions at 623 K. One of these was exposed to the atmosphere and then zeolitically dry oxygen, both at 623 K, to give In-Y[In-4(OH)(4) ([In7.6[In4(OH)(4)](7.5)[In(OH)2](2.0)I[Si121Al71O384]-FAU OR In39.6(OH)(34.0)-Y). The structures of In-Y and In-Y[In-4(OH)(4)] were determined by single crystal crystallography with synchrotron X-radiation. They were refined in the space group Fd3 (m) over bar (a = 24.863(1) and 24.518(1) angstrom) with all unique data to the final error indices R-1 = 0.050 and 0.057 for the 1110 and 1037 reflections for which F-o > 4 sigma(F-o), respectively. The In in In-Y is mostly In+; some In-5(7+) clusters are present in sodalite cavities. Upon oxidation in the presence of water, 41% of the In exited the zeolite. Most of the remainder formed In-4(OH)(4)(8+) clusters in the sodalite cavities of In-Y[In4(OH)(4)]. In-4(OH)(4)(8+) is a tetrahedrally distorted In4O4 cube with a hydrogen atom bound to each oxygen atom. In In-4(OH)(4)(8+), each In3+ ion lies opposite a double 6-ring and is 6-coordinate octahedral with three bonds to OH- anions (2.245(4) angstrom) and three to framework oxygens (2.198(5) angstrom); each OH- ion is near a single 6-ring to which it hydrogen bonds. Small amounts of In(OH)(2)(+), In2+, and In+ were also found.