Molecular orbital study of the gas phase reaction of NaxBi4 clusters with HCl (x = 1,2)

Extended Hückel calculations are performed to study how Na₂Bi₄, NaBi₄ and Bi₄ clusters and atomic Na react with HCl. We find that Bi₄ fragments act as “charge transfer catalysts” for the reaction of Na with HCl, weakening the HCl bond. Our results point to a higher reactivity of the Na₂Bi₄ cluster compared with NaBi₄, a repulsive state characterizing the reaction of Bi₄ with HCl and a “thermodynamic” impediment for the reaction of Na with HCl. These facts are in good agreement with experimental results.