Localization versus delocalization in diamine radical cations

A.M. Brouwer, P.G. Wiering, J.M. Zwier, F.W. Langkilde, R. Wilbrandt

    Research output: Contribution to journalConference articleResearchpeer-review


    The optical absorption spectrum of the radical cation of 1,4-diphenylpiperazine 2a shows a strong transition in the near-IR, and only a weak band at 445 nm, in the region where aniline radical cations normally absorb strongly. This indicates that the charge and spin are delocalized over the two equivalent aniline moieties. Introduction of a 4-methoxy group on the aromatic ring allows increased stabilization of the radical ion character on one moiety, and charge delocalization across the piperazine ring is suppressed, as shown by optical absorption and resonance Raman spectroscopy. The possibility of coexistence of localized and delocalized radical cations of diphenylpiperazine and its derivatives cannot be ruled out at present. If that were the case, the effect of the methoxy substituents is to shift the equilibrium towards the localized species.
    Original languageEnglish
    JournalActa Chemica Scandinavica
    Issue number2
    Pages (from-to)217-219
    Publication statusPublished - 1997
    Event14th International Conference on Radical Ions - Uppsala, Sweden
    Duration: 1 Jul 19965 Jul 1996
    Conference number: 14


    Conference14th International Conference on Radical Ions


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