Surprising Intrazeolitic Chemistry of Silver

New small molecules and cations have been synthesized within silver-containing zeolites, and their structures were determined using single-crystal crystallography. Some of them are the hydronitrogens N 3 H 5 and cyclo -N 3 H 3, octahedral Ag 6, and the silver halide clusters Ag 4 Cl 4, Ag 4 Br 4, and Ag 4 I 4 . The silver halide clusters within their zeolites are ordered three-dimensional arrangements of identical quantum dots. The (C 3 O 3 H 3 ) 2 2+ cation is a reduced dimer of C 3 O 3 H 3 3+ (tripyrylium); tripyrylium is planar and isoelectronic with benzene. The two rings bond together facially via their π* orbitals in an eclipsed manner with a very short interplanar distance, 2.43 Å. When a hydrated silver-exchanged zeolite is heated (to dehydrate it), Ag + ions react with framework oxygen atoms to give silver atoms and O 2 (g); this leads to crystal damage and the complete loss of crystalline diffraction. This damage, however, can be repaired and the diffraction fully restored by heating in O 2 (g). To avoid crystal damage altogether, silver-exchanged zeolites can be dehydrated at elevated temperatures in flowing O 2 (g).