skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A Site-Isolated Iridium Diethylene Complex Supported on Highly Dealuminated Y Zeolite: Synthesis and Characterization

Abstract

Highly dealuminated Y zeolite-supported mononuclear iridium complexes with reactive ethylene ligands were synthesized by chemisorption of Ir(C2H4)2(C5H7O2). The resultant structure and its treatment in He, CO, ethylene, and H2 were investigated with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies. The IR spectra show that Ir(C2H4)2(C5H7O2) reacted readily with surface OH groups of the zeolite, leading to the removal of C5H7O2 ligands and the formation of supported mononuclear iridium complexes, confirmed by the lack of Ir-Ir contributions in the EXAFS spectra. The EXAFS data show that each Ir atom was bonded to four carbon atoms at an average distance of 2.10 Angstroms, consistent with the presence of two ethylene ligands per Ir atom and in agreement with the IR spectra indicating p-bonded ethylene ligands. The EXAFS data also indicate that each Ir atom was bonded to two oxygen atoms of the zeolite at a distance of 2.15 Angstroms . The supported iridium-ethylene complex reacted with H2 to give ethane, and it also catalyzed ethylene hydrogenation at atmospheric pressure and 294 K. Treatment of the sample in CO led to the formation of Ir(CO)2 complexes bonded to the zeolite. The sharpness of the ?CO bands indicates a high degreemore » of uniformity of these complexes on the support. The iridium-ethylene complex on the crystalline zeolite support is inferred to be one of the most nearly uniform supported metal complex catalysts. The results indicate that it is isostructural with a previously reported rhodium complex on the same zeolite; thus, the results are a start to a family of analogous, structurally well-defined supported metal complex catalysts.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
960106
Report Number(s):
BNL-83092-2009-JA
Journal ID: ISSN 1932-7447; TRN: US201016%%1250
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry C; Journal Volume: 111
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION; ATMOSPHERIC PRESSURE; ATOMS; CARBON; CATALYSTS; CHEMISORPTION; ETHANE; ETHYLENE; FINE STRUCTURE; HYDROGENATION; IRIDIUM; IRIDIUM COMPLEXES; OXYGEN; REMOVAL; RHODIUM; SPECTRA; SYNTHESIS; ZEOLITES; national synchrotron light source

Citation Formats

Uzun,A., Bhirud, V., Kletnieks, P., Haw, J., and Gates, B.. A Site-Isolated Iridium Diethylene Complex Supported on Highly Dealuminated Y Zeolite: Synthesis and Characterization. United States: N. p., 2007. Web. doi:10.1021/jp073338p.
Uzun,A., Bhirud, V., Kletnieks, P., Haw, J., & Gates, B.. A Site-Isolated Iridium Diethylene Complex Supported on Highly Dealuminated Y Zeolite: Synthesis and Characterization. United States. doi:10.1021/jp073338p.
Uzun,A., Bhirud, V., Kletnieks, P., Haw, J., and Gates, B.. Mon . "A Site-Isolated Iridium Diethylene Complex Supported on Highly Dealuminated Y Zeolite: Synthesis and Characterization". United States. doi:10.1021/jp073338p.
@article{osti_960106,
title = {A Site-Isolated Iridium Diethylene Complex Supported on Highly Dealuminated Y Zeolite: Synthesis and Characterization},
author = {Uzun,A. and Bhirud, V. and Kletnieks, P. and Haw, J. and Gates, B.},
abstractNote = {Highly dealuminated Y zeolite-supported mononuclear iridium complexes with reactive ethylene ligands were synthesized by chemisorption of Ir(C2H4)2(C5H7O2). The resultant structure and its treatment in He, CO, ethylene, and H2 were investigated with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies. The IR spectra show that Ir(C2H4)2(C5H7O2) reacted readily with surface OH groups of the zeolite, leading to the removal of C5H7O2 ligands and the formation of supported mononuclear iridium complexes, confirmed by the lack of Ir-Ir contributions in the EXAFS spectra. The EXAFS data show that each Ir atom was bonded to four carbon atoms at an average distance of 2.10 Angstroms, consistent with the presence of two ethylene ligands per Ir atom and in agreement with the IR spectra indicating p-bonded ethylene ligands. The EXAFS data also indicate that each Ir atom was bonded to two oxygen atoms of the zeolite at a distance of 2.15 Angstroms . The supported iridium-ethylene complex reacted with H2 to give ethane, and it also catalyzed ethylene hydrogenation at atmospheric pressure and 294 K. Treatment of the sample in CO led to the formation of Ir(CO)2 complexes bonded to the zeolite. The sharpness of the ?CO bands indicates a high degree of uniformity of these complexes on the support. The iridium-ethylene complex on the crystalline zeolite support is inferred to be one of the most nearly uniform supported metal complex catalysts. The results indicate that it is isostructural with a previously reported rhodium complex on the same zeolite; thus, the results are a start to a family of analogous, structurally well-defined supported metal complex catalysts.},
doi = {10.1021/jp073338p},
journal = {Journal of Physical Chemistry C},
number = ,
volume = 111,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Highly dealuminated Y zeolite-supported mononuclear iridium complexes with reactive ethylene ligands were synthesized by chemisorption of Ir(C{sub 2}H{sub 4}){sub 2}(C{sub 5}H{sub 7}O{sub 2}). The resultant structure and its treatment in He, CO, ethylene, and H2 were investigated with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies. The IR spectra show that Ir(C{sub 2}H{sub 4}){sub 2}(C{sub 5}H{sub 7}O{sub 2}) reacted readily with surface OH groups of the zeolite, leading to the removal of C{sub 5}H{sub 7}O{sub 2} ligands and the formation of supported mononuclear iridium complexes, confirmed by the lack of Ir-Ir contributions in the EXAFS spectra. The EXAFSmore » data show that each Ir atom was bonded to four carbon atoms at an average distance of 2.10 {angstrom}, consistent with the presence of two ethylene ligands per Ir atom and in agreement with the IR spectra indicating {pi}-bonded ethylene ligands. The EXAFS data also indicate that each Ir atom was bonded to two oxygen atoms of the zeolite at a distance of 2.15 {angstrom}. The supported iridium-ethylene complex reacted with H{sub 2} to give ethane, and it also catalyzed ethylene hydrogenation at atmospheric pressure and 294 K. Treatment of the sample in CO led to the formation of Ir(CO){sub 2} complexes bonded to the zeolite. The sharpness of the V{sub CO} bands indicates a high degree of uniformity of these complexes on the support. The iridium-ethylene complex on the crystalline zeolite support is inferred to be one of the most nearly uniform supported metal complex catalysts. The results indicate that it is isostructural with a previously reported rhodium complex on the same zeolite; thus, the results are a start to a family of analogous, structurally well-defined supported metal complex catalysts.« less
  • No abstract prepared.
  • The reaction of Rh(C{sub 2}H{sub 4}){sub 2}(acac) with the partially dehydroxylated surface of dealuminated zeolite Y (calcined at 773 K) and treatments of the resultant surface species in various atmospheres (He, CO, H{sub 2}, and D{sub 2}) were investigated with infrared (IR), extended X-ray absorption fine structure (EXAFS), and {sup 13}C NMR spectroscopies. The IR spectra show that Rh(C{sub 2}H{sub 4}){sub 2}(acac) reacted readily with surface OH groups of the zeolite, leading to loss of acac ligands from the Rh(C{sub 2}H{sub 4}){sub 2}(acac) and formation of supported mononuclear rhodium complexes, confirmed by the lack of Rh-Rh contributions in the EXAFSmore » spectra; each Rh atom was bonded on average to two oxygen atoms of the zeolite surface with a Rh-O distance of 2.19 Angstroms. IR, EXAFS, and {sup 13}C NMR spectra show that the ethylene ligands remained bonded to the Rh center in the supported complex. Treatment of the sample in CO led to the formation of site-isolated Rh(CO){sub 2} complexes bonded to the zeolite. The sharpness of the CO bands in the IR spectrum gives evidence of a nearly uniform supported Rh(CO){sub 2} complex and, by inference, the near uniformity of the mononuclear rhodium complex with ethylene ligands from which it was formed. The supported complex with ethylene ligands reacted with H{sub 2} to give ethane, and it also catalyzed ethylene hydrogenation at 294 K.« less
  • The chemistry of formation of iridium clusters from mononuclear iridium diethylene complexes anchored in dealuminated Y zeolite, and their subsequent breakup -- all including changes in the metal-metal, metal-support, and metal-ligand interactions -- is demonstrated by time-resolved EXAFS, XANES, and IR spectroscopy.