Electronic Structure and Chemical Bonding of a Highly Stable and Aromatic Auro-Aluminum Oxide Cluster

摘要

We have produced an auro-aluminum oxide cluster, Au_2(AlO)_2~-, as a possible model for an Au-alumina interface and investigated its electronic and structural properties using photoelectron spectroscopy and density functional theory. An extremely large energy gap (3.44 eV) is observed between the lowest unoccupied and the highest occupied molecular orbitals of Au_2(AlO)_2, suggesting its high electronic stability. The global minima of both Au_2(AlO)_2~- and Au_2(AlO)_2 are found to have D_(2h) symmetry with the two Au atoms bonded to the Al atoms of a nearly square-planar (AlO)_2 unit. Chemical bonding analyses reveal a strong σ bond between Au and Al, as well as a completely delocalized π bond over the (AlO)_2 unit, rendering aromatic character to the Au_2(AlO)_2 cluster. The high electronic stability and novel chemical bonding uncovered for Au_2(AlO)_2 suggest that it may be susceptible to chemical syntheses as a stable compound if appropriate ligands can be found.