THE ADDITION OF NF2+ TO H2O AS A ROUTE TO GASEOUS PROTONATED F2NOH

NF2+ ions from the ionization of NF3 efficiently add to H2O yielding ( F2NOH)H+ under chemical ionization conditions. In keeping with the for mation process employed, collisionally activated dissociation mass spe ctrometry indicates the exclusive formation of the oxygen-protonated i somer of F2NOH. Ab initio calculations, at the GAUSSIAN-1 level of the ory, indicate that this ion is the least stable among the investigated (F2NOH)H+ isomers. However, it is trapped in a deep potential well, w hich prevents extensive isomerization to the nitrogen-protonated and t o the fluorine-protonated isomers, the latter one being by far the mos t stable protomer. The GAUSSIAN-1 potential energy profile accords wel l with the experimental features of the unimolecular decomposition of the (F2NOH2)+ ions, probed by mass analyzed ion kinetic energy (MIKE) spectrometry. Only the loss of HF was detected, characterized by a dis h-topped peak in the MIKE spectrum. Consistent with the ab initio calc ulations, the measured kinetic energy release is as large as 1.36 eV. The emerging picture has been compared with the previously reported re sults concerning the gas-phase protonation of NF3.