Theoretical study on interaction of different coordination modes of BH4 ligand with transition metal in [TM(BH4)(CO)4]− (TM = Cr, Mo)

Density functional calculations were performed on bonding and structural features of [(ηn-BH4)TM(CO4)]− (n = 1, 2, 3; TM = Cr, Mo) complexes. Calculations show that the ground state is bidentate (A) which is in good agreement with experimental results. It has been found that the bridge and terminal hydrogen atoms will interchange by two pathways: i) twist of BH4 about one of the bridge B-H (B) and ii) twist of BH4 about one of the terminal B-H (E).