Ab Initio Characterization of [(H_{3}N)BH_{3}]_{2},
[(H_{3}N)AlH_{3}]_{2}, and
[(H_{3}N)GaH_{3}]_{2}

Cramer, C. J.; Gladfelter, W. L.

* Inorg. Chem.*
**1997**, *36*, 5358.

The dimers of
[(H_{3}N)BH_{3}]_{2},
[(H_{3}N)AlH_{3}]_{2}, and
[(H_{3}N)GaH_{3}]_{2}
are characterized
as head-to-tail complexes with intermolecular H-H hydrogen bonding. In the
case of [(H_{3}N)BH_{3}]_{2}, that hydrogen
bonding is bifurcated resulting in 4
short (N)H-H(B) distances. For both
[(H_{3}N)AlH_{3}]_{2} and
[(H_{3}N)GaH_{3}]_{2},
there are
only 2 short (N)H-H(Al/Ga) distances, although the 4-atom linkage remains
far from linear. The binding energies that are calculated at the MP2 level
of theory using polarized-double-zeta basis sets are -15.1, -11.8, and -10.7
kcal/mol for
[(H_{3}N)BH_{3}]_{2},
[(H_{3}N)AlH_{3}]_{2}, and
[(H_{3}N)GaH_{3}]_{2},
respectively.
These energies appear converged to within 1 kcal/mol with respect to larger
basis sets and more complete accounting for electron correlation effects.
Binding energies from density functional calculations are within 0.3
kcal/mol of the MP2 results. All-electron and effective-core-potential
basis sets for gallium provide similar predictions.

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