The B(H2)nH2 binding energies, for n = 0–3

The complete basis set limit BH2 dissociation energy (De) is determined to be 133 cm−1. This is in good agreement with the estimate made by Alexander. The optimal structures for B(H2)n (n = 1–3) have the H2 bond axes aligned with the open-shell B 2p orbital to maximize the B to H2σ∗ donation. The H2 bond midpoints and B atom all lie in a plane. For n = 4, the analogous structure is slightly above the most stable isomer, which adds an H2 molecule above one pair of H2 molecules in B(H2)3. This non-planar B(H2)4 structure is that recently deduced from the BH2 and H2H2 potentials. The computed H2 binding energies for n = 2–4 are between about 150 and 170 cm−1 and are expected to be 5–10 cm−1 too small.