CH 5N 2 hydrazyl radicals, cations and dication radicals studied by mass spectrometry. Is the N-protonated formaldehyde hydrazon cation +CH 2NHNH 2 a bridged species?

Abstract

Isomeric CH 5N + 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., CH 3NHNH + ( 1), CH 3NNH + 2 ( 2), CH 2NHNH + 2 ( 3) and CH 2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 CH 5N + 2 ions fragment to NH + 4 + HCN and to HCNH + + NH 3, 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.