Bonding of NO2 to the Au atom and Au(111) surface: A quantum chemical study

Adsorption of NO2 on Au(lll) surface, as well as bonding in AuNO2, has been investigated by means of ab initio and density functional calculations. Fo r the AuNO2 complex, both MP2 and B3LYP calculations predict three isomers, namely trans-eta(1)-O nitrito, cis-eta(1)-O nitrito and eta(1)-N nitro iso mers, among which the latter two isomers would have comparable stability an d are candidates for the ground state of the complex. The eta(2)-O,O' nitri to isomer has also been considered and was found to be a transition state. For NO2 adsorption on Au(111), our B3LYP cluster model calculations suggest that the favorable mode would be a mu(2)-O,O' nitrito over a short bridge Au-Au pair site. The calculated vibrational frequencies of the NO2 adspecie s are in reasonably good agreement with the experimental HREELS and IRAS sp ectra.