Ab initio studies of the acetylene bromoboration mechanism

Dispersion-corrected B3LYP and CBS-MP2 studies of acetylene bromoboration mechanism will be presented with an emphasis on two reaction steps. First, possible mechanisms of the stereoconversion of dibrom(2-bromvinyl) borane from its syn to its anti isomer will be discussed in terms of an interaction between the syn isomer and HBr. The presence of HBr in the reaction mixture is unavoidable under standard experimental setup and enables an alternative mechanism of alkyne haloboration to that explored theoretically by Wang and Uchyiama [1]. Second, a possible direct generation of anti isomer of dibrom(2-bromvinyl) borane from acetylene and BBr 3 via an interaction with HBr will be discussed. Gas phase results will be compared to the implicit solvent ones in order to asess the impact of solvation on the reaction mechanism.