Zeolite-encaged iridium clusters with hydride ligands: Characterization by extended X-ray absorption fine structure, NMR, and inelastic neutron scattering vibrational spectroscopies

Fen Li, Ping Yu, Monika Hartl, Luke L. Daemen, Juergen Eckert, Bruce C. Gates

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

A family of NaY zeolite-supported iridium clusters was prepared by reductive carbonylation of Ir(CO)2(acac) sorbed in the zeolite pores to form Ir6(CO)16, which was decarbonylated by treatment in He. This method allowed preparation of samples with Ir contents as high as 33.0 wt.%. Extended X-ray absorption fine structure spectra of the decarbonylated samples indicate that the clusters are well approximated as octahedral Ir6 in the zeolite cages. The high loadings of clusters in the zeolite allowed characterization of the hydride ligands on the clusters by 1H NMR spectroscopy and inelastic neutron scattering spectroscopy. These ligands exist on the clusters even in the absence of H2 in the gas phase, presumably equilibrated with OH groups on the zeolite. The data indicate both terminal and bridging hydride ligands on the clusters. The H/Ir atomic ratio is estimated to be approximately 0.01 on the basis of the 1H NMR data and thermogravimetric analysis of the sample.

Original languageEnglish
Pages (from-to)1553-1568
Number of pages16
JournalZeitschrift fur Physikalische Chemie
Volume220
Issue number12
DOIs
StatePublished - 2006

Keywords

  • EXAFS spectroscopy
  • H NMR spectroscopy
  • IINS spectroscopy
  • Iridium
  • Supported iridium clusters
  • Zeolite NaY

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