Effect of sodium borohydride dihydrate aggregation on the barrier to elimination of hydrogen molecule: Quantum-chemical modeling

Abstract

The successive elimination of Н₂ from NaBH₄ ∙ 2Н₂O, (NaBH₄ ∙ 2Н₂O)₂, (NaBH₄ ∙ 2Н₂O)₄, and (NaBH₄ ∙ 2Н₂O)₄ · Н₂O complexes has been modeled in the framework of the cluster approach with the use of the 6-31G* basis set and hybrid density functional (B3LYP). Computations show that combination of NaBH₄ ∙ 2Н₂O into clusters and addition of one water molecule lead to a decrease in potential barriers to elimination of molecular hydrogen to 0.8–0.9 eV. Transformation of two OH groups of the В(OН)₄^- anion to give a В=O double bond with elimination of water molecule in the tetramer (NaB(OH)₄)₄ has been considered.