Low-energy Fragmentations of Five Isomeric +* Ions

Article abstract of DOI:10.1002/oms.1210250310

The low-energy fragmentation characteristics of the +* isomers +* (a), +* (b), +* (c), +* (d) and +* (e) were studied in detail by metastable ion mass spectrometry.In agreement with most earlier observations, appearance energy measurements established the potential energy surface of the isomers a, b and c, showing the intricate interrelations between them.It was concluded that a isomerizes into b prior to fragmentation by loss of *OH and H2O and into c before loss of *H and H3CO* moreover, the reversereactions do not take place on the metastable time-frame.The dominant metastable process for isomers d and e (obtained via HCN loss from glyoxime) was generation of +*.For isomer e this process was proposed to involved a rate-determining isomerization into d.It was concluded that isomers d and e do not intercommunicate with ions a, b and c prior to fragmentation.Neutralization-reionization mass spectrometry indicated that the enol form of formohydroxamic acid as well as the keto conterpart are stable in the gas phase.