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Ruthenium Carbonyl Clusters in Faujasite Cages: Synthesis and Characterization
Guo-Cheng Shen1, An Ming Liu, Masaru Ichikawa
1Lash Miller Chemical Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada, State Key Laboratory of Catalysis, Dalin Institute of Chemical Physics, Chinese Academy of Sciences, Dalin 116023, China, and Catalysis Research Center, Hokkaido University, Sapporo 060, Japan.
Abstract:
The synthesis of the intrafaujasite anchoring of ruthenium carbonyl clusters involves the adsorption of metal carbonyl species or metal ion exchange into faujasite cages followed by reductive carbonylation under an atmosphere of CO and H(2). The characterization of the structure and properties of these samples was based on a multianalytical approach, including FT-IR, UV-vis, PXRD, and EXAFS spectroscopies, CO/H(2) gas chemisorption, and (13)CO isotopic exchange. From this study, several key points emerge. (a) [Ru(3)(CO)(12)] clusters thermally diffused into dehydrated faujasite cages. (b) [Ru(3)(CO)(12)] guests in Na(56)Y were thermally activated, in a hydrogen atmosphere, generating intrafaujasite [H(4)Ru(4)(CO)(12)]. (c) Hexammineruthenium(III) complexes in Na(56)X and Na(56)Y underwent progressive thermal activation, in a CO and H(2) atmosphere. The generation process was considered to occur through conversion of the intermediates [Ru(NH(3))(5)(CO)](2+) and Ru(I)(CO)(3) to [Ru(6)(CO)(18)](2)(-). (d) A rapid (13)CO/(12)CO isotopic exchange was found to reversibly occur for [Ru(6)(CO)(18)](2)(-)/Na(56)X under H(2) coexistence. (e) Internal and external confinement of ruthenium carbonyl clusters were compared. (f) Oxidation fragmentation under an O(2) atmosphere and reductive regeneration under a CO and H(2) atmosphere were found to reversibly occur for [Ru(6)(CO)(18)](2)(-) guests. (g) Intrafaujasite anchoring of ruthenium carbonyl clusters showed a strong interaction with the extraframework Na(+) alpha-cage cations, through involvement of the oxygen end of the bridging or equatorial terminal carbonyl ligands.