Distonic ions of the "Ate" class

The gas phase synthesis, structure, and reactivity of distonic negative ion s of the "ate" class are described. "Ate"-class negative ions are readily p repared in the gas phase by addition of neutral Lewis acids, such as BF3, B H3, and AlMe3, to molecular anions, carbene negative ions, and radical anio ns of biradicals. The ions contain either localized sigma- or delocalized p i-type radical moieties remote from relatively inert berate and aluminate c harge sites. The free radical reactivity displayed by these ions appears to be independent of the charge site. As an example, the distonic alkynyl rad ical (.C=CBF3-) is highly reactive and undergoes radical coupling reactions with . NO2, NO, H2C=CH-CN, and H2C-CH-CH3. Radical-mediated group and atom transfers are observed with O-2, CS2, and CH3SSCH3. Furthermore, H-atom ab straction reactions are observed, in accordance with the predicted high C-H bond strength of this species [DH298(H-C2BF3-) = 130.8 kcal mol(-1)]. High level ab initio molecular orbital calculations on the prototype "ate"-clas s distonic ion CH2BH3- and its conventional isomer CH3BH2.- reveal that CH3 BH2.- is 3.2 kcal/mol more stable than the alpha-distonic form. However, th e calculations also show that CH3BH2.- is unstable with respect to electron detachment, and only the alpha-distonic form . CH2BH3- should be experimen tally observed in the gas phase. (J Am Soc Mass Spectrom 1999, 10, 896-906) (C) 1999 American Society for Mass Spectrometry.