INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
artículos
Título:
A density functional theory study of the electronic properties of Os(II) and Os(III) complexes immobilized on Au(111)
Autor/es:
O'BOYLE NM (O'BOYLE, NOEL M.), ALBRECHT T (ALBRECHT, TIM), MURGIDA DH (MURGIDA, DANIEL H.), CASSIDY L (CASSIDY, LYNDA), ULSTRUP J (ULSTRUP, JENS), VOS JG (VOS, JOHANNES G.)
Revista:
INORGANIC CHEMISTRY
Referencias:
Año: 2007 vol. 46 p. 117 - 124
ISSN:
0020-1669
Resumen:
We present a density functional theory (DFT) study of an osmium
polypyridyl complex adsorbed on Au(111). The osmium polypyridyl complex
[Os(bpy)(2)(P0P)Cl](n+) [bpy is 2,2'-bipyridine, P0P is
4,4'-bipyridine, n = 1 for osmium(II), and n = 2 for osmium(III)] is
bound to the surface through the free nitrogen of the P0P ligand. The
calculations illuminate electronic properties relevant to recent
comprehensive characterization of this class of osmium complexes by
electrochemistry and electrochemical scanning tunneling microscopy. The
optimized structures for the compounds are in close agreement with
crystallographic structures reported in the literature. Oxidation of
the complex has little effect on these structural features, but there
is a substantial reordering of the electronic energy levels with
corresponding changes in the electron density. Significantly, the
highest occupied molecular orbital shifts from the metal center to the
P0P ligand. The surface is modeled by a cluster of 28 gold atoms and
gives a good description of the effect of immobilization on the
electronic properties of the complexes. The results show that the
coupling between the immobilized complex and the gold surface involves
electronic polarization at the adsorbate/substrate interface rather
than the formation of a covalent bond. However, the cluster is too
small to fully represent bulk gold with the result that, contrary to
what is experimentally observed, the DFT calculation predicts that the
gold surface is more easily oxidized than the osmium(II) complex.