Sodium ionic clusters have been prepared by chemical vapor deposition of sodium metal at 225 degrees C and 1 x 10(-4) Torr in NaX zeolites. A maximum loading of approximately 1.2 wt % sodium was vaporized onto dehydrated NaX zeolite. Ionic clusters prepared in this study have been determined to have the formula Na-6(5+). In this complex the sodium ions are arranged in octahedral geometries in the sodalite cages of NaX zeolite. Identification of these species was accomplished by electron paramagnetic resonance, magic angle spinning nuclear magnetic resonance. Fourier transform infrared spectroscopy, luminescence spectroscopy, and X-ray diffraction experiments. These ionic clusters have a localized electron trapped in the center of the octahedra, giving rise to a color center. Infrared analysis of pyridine adsorption onto NaX and NaX exposed to sodium vapor (Na(v)/NaX) revealed that initial Bronsted acidities of untreated NaX zeolites are low and that a complete loss of Bronsted acidity is observed upon treatment with Na vapor. The catalytic properties of materials exposed to sodium vapor have been studied in isomerization reactions. Defect sites or holes on framework oxygen sites are proposed as the source of catalytic activity at elevated temperatures (>340 degrees C). A catalytic mechanism for isomerization of cyclopropane to propylene over positively charged defect sites associated with Na-6(5+) clusters in Na(v)/NaX zeolites is discussed. Activation energies, based on Arrhenius plots for first-order reactions, and rates of propylene formation are determined for cyclopropane isomerization reactions over defect sites in Na(v)/NaX catalysts. Two reaction pathways are proposed for the treatment of sodium vapor on these materials. The dominating reaction produces Na-6(5+) clusters in the sodalite cages of NaX zeolites. In a second reaction, Na vapor reduces Bronsted acid sites on terminal hydroxyl groups. The latter reaction leads to the formation of hydridic species on framework silicon atoms at high temperatures and the generation of-electron holes on framework oxygen. Activation of defect sites has been observed only at high temperatures. Electron paramagnetic resonance studies show that naphthalene, sublimed on defect sites, results in the formation of naphthalene radicals.