Potential Surfaces for Unimolecular and Bimolecular Gas Phase Reactions of BHmCln Calculated at the G2 Level of Theory

Transition structures and reaction paths for the BH m Cl n system have been characterized at the MP2(full)/6-31G(d) level of theory; heats of reaction and barriers have been computed at the G2 level of theory. Calculations show that the insertion reactions of BH m Cl n into H 2 and HCl ( m + n = 0, 1, 2) occur by highly distorted, non-least motion transition states, with barriers that increase with chlorine substitution on boron. Hydrogen abstraction from BH and BH 3- n Cl n by chlorine proceeds with little or no barrier by a linear transition state. By contrast, BH 3- n Cl n + H → BH 2- n Cl n + H 2 occurs by an addition−elimination path via a tetracoordinate intermediate. Likewise, BH 2- n Cl n + X → BH 1- n Cl n + HX or BH 2- n Cl n -1 + XCl (X = H, Cl) are also addition−elimination processes. Abstraction of Cl from BCl and BH 3- n Cl n by H is endothermic and occurs by a bent transition state.