Ab initio study of the formation of B_3H_7 derivative from B_3H_8~- anion protonation

摘要

Formation of B_3H_7 species from the protonation of B_3H_8~- has been studied by ab initio calculations at the HF and correlated MP2 levels using extended basis set 6-31+G~(**).Two elementary processes,B_3H_8~-+H~+→B_3H_9and B_3H_7+H_2,have been investigated.The calculated absolute values of B_3H_8~-+H~+→B_3H_9protonation energy are very high(above 314 kcal mol~(-1)).Loss of molecular hydrogen from B_3H_9proceeds with an activation barrier above 12 kcal mol~(-1),leading to a B_3H_7 one-bridged structure.The activation barrier of reverse reaction is found non-negligible when the zero-point energy correction is added.The calculated energy and activation barriers of B_3H_7 rearrangement are small,confirming the fluxional behaviour for this species.However,a mechanism of B_3H_7 formation is proposed.The inclusion of a solvent reaction field using water as a solvent(ε=78.54)has a small influence on the energies and molecular properties.