Evidence for the formation of acyclic ions from the radical cations and cyclic ions from the protonated molecules of ¿,¿-diamines upon loss of ammonia

Ana M. Fernandes, A.J. Ferrer Correia, R.H. Fokkens, N.M.M. Nibbering

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    Abstract

    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.
    Original languageUndefined
    Pages (from-to)55-63
    JournalInternational journal of mass spectrometry
    Volume217
    Issue number1-3
    DOIs
    Publication statusPublished - 2002

    Keywords

    • Ammonia loss
    • Collision-induced dissociation
    • Ion structures
    • IR-74723
    • METIS-209406
    • α
    • ω-Diamines
    • Ion/molecule reactions

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