The Pentagallium Cation in Zeolite Y. Preparation and Crystal Structure of Ga42Tl9.3-Si121Al71O384 Containing Ga57+, Ga+, Ga2+, Ga3+, and Tl+

The extraframework gallium cations Ga-5(7+), Ga+, Ga2+, and Ga3+ have been introduced into zeolite Y. Ga,Tl-Y (Ga42Tl9.3-Y or vertical bar(Ga-5(7+))(5.8)Ga6.6+Ga2+ Ga-4.8(1.5)3+ Tl-9.3(+)vertical bar[Si121Al71O384]-FAU) was prepared by the reaction of Tl-71-Y with Ga-0 under anhydrous conditions at 623 K Its structure was determined by single-crystal crystallography with synchrotron X-radiation, and its composition was confirmed by energy dispersive X-ray analysis. The structure was refined in the space group Fd (3) over barm (a = 24.527(1) angstrom) with all 1126 unique data; the final error index, R-1 = 0.074, was calculated using only the 935 reflections with F-o > 40(-)(F-o). Ga-0 reacted with 87% of the Tl+ ions in the zeolite, mostly to give Ga-5(7+) cations (centered tetrahedral, Ga-Ga = 2.512(3) angstrom). Ga-5(7+) centers 5.8 of the 8 sodalite cavities per unit cell; each terminal atom (at site I') bonds to three framework oxygen atoms of a double 6-ring (Ga-O = 2.050(5) angstrom and O-Ga-O = 99.0(2)(degrees)). The remaining Ga ions occupy five crystallographically distinct cationic sites: 2.3 Ga+ at site I', 4.3 Ga+ at site II, 2.1 Ga2+ at a second site II, 2.7 Ga2+ at site III', and 1.5 Ga3+ at a second site I'. The gallium ions at sites I' and II bond only to three 6-ring oxygen atoms; those at sites II and III' extend into the supercage and are easily accessible for sorption and catalysis. All Tl+ ions occupy supercage sites.