Theoretical studies of Au m and PtAu n clusters and their N 2 and O 2 adsorption complexes

Small homonuclear Au m ( m ≤ 5) and bimetallic PtAu n ( n ≤ 4) clusters were studied using density functional theory. Both homonuclear and bimetallic clusters tend to form compact two‐dimensional structures. All the low‐lying Au m clusters have delocalized highest occupied molecular orbitals (HOMOs), whereas all the PtAu n clusters have more localized HOMOs on the Pt atom. The localized HOMO makes the PtAu n clusters more regioselective toward electrophilic reactions than the Au m clusters. Adsorptions of N 2 and O 2 onto these metal clusters were further studied. In N 2 adsorption, the metal clusters donate their electrons primarily to the σ * orbitals of N 2 to form end‐on complexes preferably. In O 2 adsorption, complicated π orbital interactions between the cluster and O 2 dominate to form side‐on complexes with relatively larger binding energies. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012