The structural characterization of the ions generated by the electron ionization-induced loss of ammonia from the molecular ions of α,ω-diamines, using ion/molecule reactions in combination with collision-induced dissociation (CID) studies, is described. The results of the experiments of ion/molecule reactions using dimethyl disulfide exclude the distonic radical cation structure for those long-lived ions proposed earlier by other authors for ions generated within a few microseconds following ionization. The unimolecular and CID characteristics of the ions [M---NH3]√+ of 1,4-diaminobutane and 1,5-diaminopentane and of their fragment ion m/z=56, are discussed in terms of the structures CH3CH2CH=CHNH2√+ and CH3CH2CH2CH=CHNH2√+ for the ions [M---NH3]√+, respectively. The structure of the closed shell ions resulting from loss of ammonia from the protonated α,ω-diamines was also probed through the CID spectra of model ions prepared by chemical ionization with methane in the chemical ionization source of the mass spectrometer.
- Ammonia loss
- Collision-induced dissociation
- Ion structures
- Ion/molecule reactions
Fernandes, A. M., Correia, A. J. F., Fokkens, R. H., & Nibbering, N. M. M. (2002). Evidence for the formation of acyclic ions from the radical cations and cyclic ions from the protonated molecules of ¿,¿-diamines upon loss of ammonia. International journal of mass spectrometry, 217(1-3), 55-63. https://doi.org/10.1016/S1387-3806(02)00535-3