title: Molecular mechanism for H2 release from BH3NH3, including the catalytic role of the Lewis acid BH3.
abstract: Electronic structure calculations using various methods, up to the coupled-cluster CCSD(T) level, in conjunction with the aug-cc-pVnZ basis sets with n = D, T, and Q, extrapolated to the complete basis set limit, show that the borane molecule (BH3) can act as an efficient bifunctional acid-base catalyst in the H2 elimination reactions of XHnYHn systems (X, Y = C, B, N). Such a catalyst is needed as the generation of H2 from isoelectronic ethane and borane amine compounds proceeds with an energy barrier much higher than that of the X-Y bond energy. The asymptotic energy barrier for H2 release is reduced from 36.4 kcal/mol in BH3NH3 to 6.0 kcal/mol with the presence of BH3 relative to the molecular asymptote. The NH3 molecule can also participate in a similar catalytic process but induces a smaller reduction of the energy barrier. The kinetics of these processes was analyzed by both transition-state and RRKM theory. The catalytic effect of BH3 has also been probed by an analysis of the electronic densities of the transition structures using the atom-in-molecule (AIM) and electron localization function (ELF) approaches.
authors.affiliation: Department of Chemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, USA.
authors.forename: Minh Tho
authors.initials: MT
authors.lastname: Nguyen
authors.forename: Vinh Son
authors.initials: VS
authors.lastname: Nguyen
authors.forename: Myrna H
authors.initials: MH
authors.lastname: Matus
authors.forename: G
authors.initials: G
authors.lastname: Gopakumar
authors.forename: David A
authors.initials: DA
authors.lastname: Dixon