Theoretical study of dodecahydro-closo-decaborane B10H12, the diprotonated boron cluster B10H 10 2-

The electronic and geometric structures of different isomers of the closo-B10H12 boron cluster have been calculated by the density functional theory method (in the B3LYP/6-311++G**//B3LYP/6-31G* approximation). The compound is considered to be the diprotonated (H*) analogue of the well-studied B10H (10) (2-) anion and serves as a model system. The increase in the relative energies of isomers and the preferred location of the extra H* protons near the opposite B(1) and B(10) "poles" are consistent with the charge separation (in the framework of the Mulliken population analysis) between B(1) and B(10). The reactions of migration of one or simultaneously two H* protons in B10H12 over the boron polyhedron have been considered, and the corresponding energies of elementary events E and activation barriers h have been estimated. The elementary events have been predicted in which both H* protons simultaneously move along the trajectories near the opposite B(1) and B(10) poles of the B10H (10) (2-) polyhedron with the same or opposite changes in the angles determining the H* position with respect to the B(1)-B(10) axis. The activation barrier to the "opposite" migration of the H* protons has been assessed to be h similar to 1.2 kcal/mol, whereas for the migration of the H* protons in the same direction, h similar to 1.4 kcal/mol. The H* proton transfer from the position near the B(1) pole to the position near the opposite B(10) pole is hindered, and higher activation barriers on the order of h similar to 13-15 kcal/mol should be overcome for this transfer to occur.