Models for Partially Hydroxylated Silica and Alumina and the Modeling of Metal-Support Interaction of Triosmium Clusters on Silica and Alumina
| Autor: | Leh-Yeh Hsu, Lindora D'Ornelas, Sheldon G. Shore, A. Choplin, Jean-Marie Basset |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
Steric effects
010405 organic chemistry Stereochemistry Chemistry chemistry.chemical_element 010402 general chemistry Heterogeneous catalysis 01 natural sciences Catalysis 0104 chemical sciences Metal symbols.namesake Crystallography visual_art symbols visual_art.visual_art_medium Cluster (physics) Molecule Osmium Physical and Theoretical Chemistry van der Waals force |
| Zdroj: | Journal of Catalysis. 149:159-170 |
| ISSN: | 0021-9517 |
| DOI: | 10.1006/jcat.1994.1281 |
| Popis: | Surface complexes formed from the reactions of Os 3 (CO) 12 with silica and alumina are generally represented as (μ-H)(μ-OSi ) Os 3 (CO) 10 and (μ-H)(μ-OAl ;)Os 3 (CO) 10 , with a surface oxygen atom bridging two osmium atoms, and as (μ-OSi ) 2 Os 3 (CO) 10 and (μ-OAl )Os 3 (CO) 10 , in which two surface oxygens bridge the same two osmium atoms. These surface complexes have been modeled employing computer graphics techniques. Models for partially hydroxylated silica and gamma-alumina have been developed and metal-support interaction between (μ-H)Os 3 (CO) 10 , Os 3 (CO) 10 , and local regions of support surfaces have been studied. Van der Waals interaction energies, nonbonded contacts as a function of orientation of the cluster with respect to the surface, and possible relaxation of the cluster have been considered. The results indicate that the (μ-H)Os 3 (CO) 10 unit appears to bind readily to selected oxygen sites of the silica and alumina with little or no steric restraint. On the other hand, the cluster unit Os 3 (CO) 10 is not readily accommodated on either the silica or alumina surfaces by means of a double-oxygen bridge to two osmium atoms without extreme disruption of the surface or the cluster. |
| Databáze: | OpenAIRE |
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