Evidence for isomeric radical cations derived from diolefin dimers. A comparison between gas phase and solution

Organic radical cations play an important role in a variety of biological and chemical processes. In order to evaluate the structures and reactions of radical cations derived from diolefin dimers, results obtained in the gas phase (by Fourier transform mass spectrometry) and in solution (by chemically induced dynamic nuclear polarization) are compared. Upon electron impact in the gas phase, the dimers formed doubly linked (e.g. A) and singly linked (e.g. B) "molecular ions" and suffered two-bond cleavage to form monomer ions. In solution on the other hand, photo-induced electron transfer generated either the singly linked or the doubly linked species; two-bond cleavage is clearly the exception.