CH5N2 hydrazyl radicals, cations and dication radicals studied by mass spectrometry. Is the N-protonated formaldehyde hydrazon cation +CH2NHNH2 a bridged species?

Isomeric CH5N+2 cations, radicals and dication radicals have been studied by a variety of mass spectrometry based techniques (metastable ion-, collisional activation-, collision induced dissociative ionization-, neutralization-reionization-, charge stripping/charge separation- and charge stripping/electron-capture induced decomposition mass spectroscopy), by energetical measurements and labeling experiments. Four distinct singly charged ions could be identified, viz., CH3NHNH+ (1), CH3NNH+2 (2), CH2NHNH+2 (3) and CH2NNH+3 (4).Ions 1, 2 and 3 are generated by direct bond cleavage reactions in 1,2-dimethylhydrazine, 1,1-dimethylhydrazine and 2-hydrazinoethanol molecular ions, respectively. Ions 4, it is proposed, are formed by isomerization of 3 and the possibility is entertained that 3 and 4 collapse to the bridged structure . Metastable CH5N+2 ions fragment to NH+4 + HCN and to HCNH+ + NH3, and mechanisms for these reactions are proposed. Ions 1 and 2 can be reduced to the corresponding hydrazile radicals but only a minor fraction of ions 3 and 4 survives neutralization. The latter ions, however, are easily oxidized to the corresponding dication radicals and (as shown by electron capture-induced decomposition) these ions retain their structure during flight.