A Theoretical Study on Small Iridium Clusters: Structural Evolution, Electronic and Magnetic Properties, and Reactivity Predictors

The structural, electronic, and magnetic properties of iridium clusters with sizes of n = 2-15 are investigated by employing the generalized gradient approximation of density functional theory. Simple cube evolution pattern is revealed for Ir2-15 clusters, as predicted by previous reports. It is remarkable that for Ir-10, Ir-11 clusters, new generated isomers with higher stabilities relative to those reported in previous studies are obtained. The even-sized clusters are more stable than the odd-sized species. The Ir-Ir bonds in the cubic Ir-8 and Ir-12 clusters, which are considered as the basic units in the structural evolution present covalent character. Starting from n = 8, the magnetic moments of Ir-n clusters decrease sharply. The moments of magnetic clusters show 5d characters. The reactive site selectivity of studied clusters with n = 5-15 is analyzed with condensed Fukui function. The capped atoms in certain clusters (Ir-9, Ir-10, Ir-11, and Ir-13) generally show extraordinary activity for both nucleophilic and electrophilic attack.