Iridium Clusters in NaX Zeolite Cages: Synthesis, Reactivity, and Characterization by Infrared and Extended x-ray Absorption Fine Structure Spectroscopies

[Ir(CO){sub 2}(ACAC)] in the pores of NaX zeolite was treated in CO and converted into iridium carbonyl clusters, which are suggested on the basis of infrared spectra and comparisons with solution chemistry to be [IIr{sub 4}CO{sub 11}]{sup -}, which was subsequently converted into clusters that are suggested to be [Ir{sub 6}(CO){sub 15}]{sup 2-}. The former clusters in the NaX zeolite were decarbonylated by treatment in He followed by H{sub 2} at 573 K and characterized by extended X-ray absorption fine structure spectroscopy. The Ir-Ir first-shell coordination number (3.0) indicates that the clusters were predominantly Ir{sub 4} tetrahedra. The clusters postulated to be [Ir{sub 6}(CO){sub 12}]{sup 2} were reversibly fragmented and reformed in the cages. 52 refs., 3 figs., 3 tabs.