Redox Chemisty of Tantalum Clusters on Silica Characterized by X-ray Absorption Spectroscopy

Journal Article · Sun Jan 01 04:00:00 EST 2006 · J. Phys. Chem. B

DOI:https://doi.org/10.1021/jp0629386· OSTI ID:914199

Nemana, S; Gates, B

SiO{sub 2}-supported clusters of tantalum were synthesized from adsorbed Ta(CH{sub 2}Ph){sub 5} by treatment in H{sub 2} at 523 K. The surface species were characterized by X-ray absorption spectroscopy (extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray absorption near edge spectroscopy (XANES)) and ultraviolet-visible spectroscopy. The EXAFS data show that SiOO{sub 2}-supported tantalum clusters were characterized by a Ta-Ta coordination number of approximately 2, consistent with the presence of tritantalum clusters, on average. When these were reduced in H{sub 2} and reoxidized in O{sub 2}, the cluster nuclearity remained essentially unchanged, although reduction and oxidation occurred, respectively, as shown by XANES and UV-vis spectra; in the reoxidation, the tantalum oxidation state change was approximately two electronic charges per tritantalum cluster. The data demonstrate an analogy between the chemistry of group 5 metals on the SiO{sub 2} support and their chemistry in solution, as determined by the group of Cotton.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 914199
• Report Number(s): BNL--78767-2007-JA
• Journal Information: J. Phys. Chem. B, Journal Name: J. Phys. Chem. B Vol. 110; ISSN 1089-5647; ISSN JPCBFK
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COORDINATION NUMBER
MOLECULAR CLUSTERS
REDOX REACTIONS
SILICON OXIDES
SUBSTRATES
SYNTHESIS
TANTALUM
national synchrotron light source