Chemistry of Tantalum Clusters in Solution And on SiO(2) Supports: Analogies And Contrasts

Journal Article · Wed Jun 03 04:00:00 EDT 2009 · Langmuir 23:8845,2007

OSTI ID:953955

Nemana, S; Okamoto, N L; Browning, N D; Gates, B C

Tantalum clusters have been synthesized from Ta(CH{sub 2}Ph){sub 5} on the surface of porous fumed SiO{sub 2}. When these clusters are small, incorporating, on average, several Ta atoms, their chemistry is similar to that of molecular tantalum clusters (and other early transition-metal) clusters. For example, The Ta-Ta bonds in these small supported clusters have been characterized by extended X-ray absorption fine structure (EXAFS), IR, and UV-vis spectroscopy, being similar to those in molecular analogues. The redox reactions of the supported clusters, characterized by X-ray absorption near-edge structure, are analogous to those of early transition-metal clusters in solution. In contrast to the largest of these clusters in solution and in the solid state, those supported on SiO{sub 2} are raftlike, facilitating the substantial metal-support-oxygen bonding that is evident in the EXAFS spectra. Samples consisting of tantalum clusters on SiO{sub 2} catalyze alkane disproportionation and the conversion of methane with n-butane to give other alkanes, but catalytic properties of analogous clusters in solution have barely been explored.

• Research Organization: Stanford Linear Accelerator Center (SLAC)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 953955
• Report Number(s): SLAC-REPRINT-2009-437
• Journal Information: Langmuir 23:8845,2007, Journal Name: Langmuir 23:8845,2007 Journal Issue: 17 Vol. 23; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
ABSORPTION SPECTROSCOPY
ALKANES
ATOMS
BONDING
CONVERSION
FINE STRUCTURE
METHANE
OXIDATION
Other
OTHER
REDOX REACTIONS
REDUCTION
SILICON OXIDES
SOLIDS
SOLUTIONS
SPECTRA
SPECTROSCOPY
SURFACES
TANTALUM