The role of solvent and of species generated in situ on the kinetic acceleration of aminoborane oligomerization.

The unexpected role of nucleophilic assistance of solvents and intermediates generated in situ in catalyzing NH2BH2 oligomerization is revealed in a computational study. The rate-determining free-energy barrier E(A) that is due to solvent participation for conversion of NH2BH2 to cyclotriborazane (NH2BH2)3 is only 12.7 kcal  mol(-1), whereas without nucleophilic assistance it is as high as 29.0 kcal  mol(-1) in THF (see figure).