The Gas Phase Ion Chemistry of BH2+

The reactions of BH 2 + with hydrogen and some simple hydrocarbons and hydrides have been studied in the gas phase with a tandem flowing afterglow-selected ion flow tube apparatus. Reaction rate constants are reported along with branching ratios for multichannel reactions. The mechanisms of reactions have been elucidated by using deuterium labeling experiments and post-SCF level molecular orbital calculations. A general mechanism for the reaction BH 2 + + RH → HBR + + H 2 (R = OH, NH 2, SH, CH 3, C 2 H 5, C 2 H 3, C 2 H) is suggested along with alternative and secondary pathways. Predicted intermediates have been generated by independent approaches. The unusual species BH 4 + and BH 6 + have been generated and their structures assessed computationally. The role of BH 4 + in the isotope exchange reaction of BH 2 + with D 2 is discussed in detail. Parallels are drawn between reactions of BH 2 + and CH 3 + in the gas phase and differences are revealed and discussed.