A theoretical study on the clusters Irn with n = 4, 6, 8, 10

For investigating the hydrocarbon hydrogenation catalytic activity of metal particles which become size-dependent as the particles which become so small as clusters, the clusters Irn with n = 4, 6, 8, 10 are studied by using effective core potential (10s5p3d)/[2s1p1d] basis set of Gaussian-94 program. The calculated result shows that for spin singlet, the clusters Ir4 and Ir6 without solid support are of size-dependent reactivity, whereas the clusters Ir8 and Ir10 without solid support may be of size-independent reactivity, even they may not possess catalytic activity.