Chemistry of Tantalum Clusters in Solution and on SiO2 Supports: Analogies and Contrasts

Journal Article · Mon Jan 01 04:00:00 EST 2007 · Langmuir

DOI:https://doi.org/10.1021/la063769j· OSTI ID:929947

Nemana, S; Okamoto, N; Browning, N; Gates, B

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: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 929947
• Report Number(s): BNL--80542-2008-JA
• Journal Information: Langmuir, Journal Name: Langmuir Vol. 23; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
ABSORPTION SPECTROSCOPY
ALKANES
ATOMS
CHEMICAL BONDS
CHEMISTRY
CONVERSION
FINE STRUCTURE
METHANE
OXIDATION
REDOX REACTIONS
REDUCTION
SOLIDS
SOLUTIONS
SPECTRA
SPECTROSCOPY
SURFACES
TANTALUM
X-RAY SPECTROSCOPY
national synchrotron light source