THE GAS-PHASE ION CHEMISTRY OF BH2+

The reactions of BH2+ with hydrogen and some simple hydrocarbons and h ydrides have been studied in the gas phase with a tandem flowing after glow-selected ion flow tube apparatus. Reaction rate constants are rep orted along with branching ratios for multichannel reactions. The mech anisms of reactions have been elucidated by using deuterium labeling e xperiments and post-SCF level molecular orbital calculations. A genera l mechanism for the reaction BH2+ + RH --> HBR+ + H-2 (R OH, NH2, SH, CH3, C2H5, C2H3, C2H) is suggested along with alternative and secondar y pathways. Predicted intermediates have been generated by independent approaches. The unusual species BH4+ and BH6+ have been generated and their structures assessed computationally. The role of BH4+ in the is otope exchange reaction of BH2+ with D-2 is discussed in detail. Paral lels are drawn between reactions of BH2+ and CH3+ in the gas phase and differences are revealed and discussed.