Reactivity of the CHBr2+ Dication toward Molecular Hydrogen

Abstract : Structural aspects as well as the stability and reactivity of the CHBr2+ dication are studied both experimentally and theoretically. Translational energy distributions of the CHBr+ products from charge transfer between CHBr2+ and Kr indicate that the dication exists in two isomeric forms, H−C−Br2+ and C−Br−H2+. In the reaction of CHBr2+ with H2, the dominant channel corresponds to proton transfer leading to CBr+ + H3+. Other reaction channels involve the formation of the intermediates CH3Br2+ and CH2BrH2+, respectively. Both of the latter dications can either lose a proton to form CH2Br+ or undergo a spin-isomerization followed by cleavage of the C−Br bond. The proposed mechanisms are supported by DFT calculations and deuterium labeling experiments.