Structural Characterization of Supported RhI(CO)2/纬-Al2O3 Catalysts by Periodic DFT Calculations
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- 作者：Otello M. Roscioni ; John M. Dyke ; John Evans
- 刊名：Journal of Physical Chemistry C
- 出版年：2013
- 出版时间：September 26, 2013
- 年：2013
- 卷：117
- 期：38
- 页码：19464-19470
- 全文大小：321K
- 年卷期：v.117,no.38(September 26, 2013)
- ISSN：1932-7455
文摘
Microscopic structures of monodispersed rhodium dicarbonyl species chemisorbed on a ceramic metal-oxide support (纬-alumina) have been obtained by density functional theory (DFT) calculations with periodic boundary conditions applied. Several minimum energy structures of species were obtained and their relative energies indicate that, in the most energetically stable geometry, the rhodium atom is coordinated in a square-planar environment and forms a four-membered Rh鈥揙鈥揂l鈥揙 ring, with one Al atom octahedrally coordinated. Another docking geometry, close lying in energy, also has a square-planar coordination for the rhodium atom and involves a six-membered Rh鈥揙鈥揂l鈥揙鈥揂l鈥揙 ring with one Al octahedrally coordinated and one Al tetrahedrally coordinated. Computed bond lengths were found to be in reasonable agreement with experimental bond lengths as determined by EXAFS spectroscopy. Theoretical Rh K-edge XANES spectra suggest that the pre-edge region probes electronic states localized on the RhI(CO)2 unit, while postedge features probe the electronic states arising from the RhI(CO)2 interaction with the support, which partly depends on the docking geometry of the RhI(CO)2 units.