A detailed study of the electronic structure of Fe_3 cluster and associative adsorption of N_2 to this cluster: A natural bond orbital analysis

摘要

To develop a detailed picture of the bare Fe_3 cluster structure, the nature of chemical bonding in this metal cluster is investigated by natural bond orbital (NBO) and natural resonance theory (NRT) analyses. The first part of the study clearly shows that the main factor governing the ground-state geometry of this cluster is the delocalized nature of the valence electrons. Highly unsaturated structure and the charge transfer list of ω_i → ωj* NBO interactions of the parent reference Fe_3 structure draw ones attention to the possible candidate structures presenting the correct electronic structure consistent with the observed optimized geometry of Fe_3. In the other part of the study, different established modes of nitrogen coordination on Fe_3 cluster are investigated. It is found that the most favored adsorption site for the associative attachment of N _2 is the bridge site, with the binding energy of -17.6 kcal/mol. NBO analysis is also applied to present a detailed discussion of the metal-ligand interactions and the predominate role of the delocalized valence electrons.