Generation and characterization of ionic and neutral dihydroxy boron B(OH)2+/0 in the gas phase

The dicoordinated borinium ion, dihydroxyborinium, B(OH)2+ is generated from methyl boronic acid CH3B(OH)2 by dissociative electron ionization and its connectivity confirmed by collisional activation. Neutralization–reionization (NR) experiments on this ion indicate that the neutral B(OH)2 radical is a viable species in the gas phase. Both vertical neutralization of B(OH)2+ and reionization of B(OH)2 in the NR experiment are, however, associated with particularly unfavorable Franck-Condon factors. The differences in adiabatic and vertical electron transfer behavior can be traced back to a particular π stabilization of the cationic species compared to the sp2-type neutral radical. Thermochemical data on several neutral and cationic boron compounds are presented based on calculations performed at the G2 level of theory.