{sup 129}Xe NMR spectroscopy of metal carbonyl clusters and metal clusters in zeolite NaY

Journal Article · Wed Aug 25 04:00:00 EDT 1999 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja990532j· OSTI ID:20000134

Labouriau, A; Panjabi, G; Enderle, B; Peitrass, T; Gates, B C; Earl, W L; Ott, K C

[Ir{sub 4}(CO){sub 12}] and [Ir{sub 6}(CO){sub 16}] were synthesized in the pores of zeolite NaY by reductive carbonylation of sorbed [Ir(CO){sub 2}(acac)], and [Rh{sub 6}(CO){sub 16}] was similarly synthesized from [Rh(CO){sub 2}(acac)]. The supported metal carbonyl clusters were decarbonylated to give supported clusters modeled on the basis of extended X-ray absorption fine structure spectra as Ir{sub 4}, Ir{sub 6}, and Rh{sub 6}, respectively. The supported metal carbonyl clusters and the supported metal clusters formed by their decarbonylation were investigated by {sup 129}XeNMR spectroscopy at temperatures in the range of 100--305 K. As the temperature increased, the chemical shift decreased. The curves representing the chemical shift as a function of temperature for xenon sorbed on the zeolite that contained clusters modeled as Ir{sub 4}, Ir{sub 6}, and Rh{sub 6} were all essentially the same and hardly different from that observed for the bare zeolite NaY. This comparison leads to the conclusion that xenon is less strongly adsorbed on the decarbonylated metal clusters than on the zeolite framework. Larger chemical shifts were observed for the zeolites containing the metal carbonyl clusters, with the largest being observed for the zeolite containing [Ir{sub 4}(CO){sup 12}]. These results are explained on the basis of the cluster sized and NaY zeolite geometry. The authors suggest that the contact between xenon and [Ir{sub 4}(CO){sub 12}] cluster is better than that between xenon and [Ir{sub 6}(CO){sub 16}] or xenon and [Rh{sub 6}(CO){sub 16}] clusters because these two larger clusters almost fill the zeolite supercages and exclude xenon, whereas [Ir{sub 4}(CO){sub 12}] in the supercages is small enough to allow entry of the xenon.

• Research Organization: Los Alamos National Lab., NM (US)
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: W-7405-ENG-36; FG05-89ER45384; AC02-76CH00016
• OSTI ID: 20000134
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 33 Vol. 121; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
40 CHEMISTRY
CARBONYLS
IRIDIUM
METALS
NUCLEAR MAGNETIC RESONANCE
XENON 129
ZEOLITES