Hydrogenation of aluminium hexamer: Ab initio molecular orbital theory and density functional theory study

The detailed mechanism of the reaction of aluminium hexamer with H-2 molecule to form a dihydride has been studied using ab initio molecular orbital theory and density functional theory. For the bare Al-6 cluster, the singlet state distorted octahedron (D-3d) is found to be the ground-state structure. The hydrogenation reaction of the singlet state Al-6 cluster is described by the lack of activation barrier for H-2 cleavage, consistent with experiment. The most stable product isomer involves two H bridges on the Al-Al edges of the same Al-Al-Al face of the Al-6 octahedron and its formation is exothermic by about 30 kcal/mol. (C) 2008 Elsevier B. V. All rights reserved.