Proton affinities of borane-amines: consequences on dihydrogen bonding.

The calculated proton affinities of four borane-amines using Gaussian-2 theory have been found to be comparable to conventional bases such as water, methanol, and ammonia. On the other hand the structure of protonated borane-ammonia, [HBH(3)-NH(3)](+), is found to be drastically different from that of protonated ammonia, [HNH(3)](+), and can appropriately be described as a eta(2)-H(2) complex with [BH(2)-NH(3)](+) molecular cation. Further, the proton affinities of borane-amines are related to the ease of H(2) elimination.