Journal of Physical Chemistry A, Vol.109, No.46, 10582-10586, 2005
Molecular orbital investigation of the protonated H2X2AlNHn(CH3)(3-n)(+) (X = F, Cl, and Br; n=0-3) complexes
Structures of protonated alane-Lewis base donor-acceptor complexes H2X2AlNHn(CH3)(3-n)(+) (X = F, Cl, and Br; n = 0-3) as well as their neutral parents were investigated. All the monocations H(2)X(2)AINH(n)(CH3)(3-n)(+) are Al-H protonated involving hypercoordinated alane with a three-center two-electron bond and adopt the C-s symmetry arrangement. The energetic results show that the protonated alane-Lewis complexes are more stable than the neutral ones. They also show that this stability decreases on descending in the corresponding periodic table column from fluorine to bromine atoms. The calculated protonation energies of HX(2)A1NH(n)(CH3)(3-n) to form H(2)X(2)AINH(n)(CH3)(3-n)(+) were found to be highly exothermic. The possible dissociation of the cations H(2)X(2)AINH(n)(CH3)(3-n)(+) into X(2)AINH(n)(CH3)(3-n)(+) and molecular H-2 is calculated to be endothermic.