USE OF ISOTOPIC LABELING IN ESTABLISHING REACTION-MECHANISMS - CD3++C2H6

The reaction of CD3+ with C2H6 has been reinvestigated by the Fourier- transform ion cyclotron resonance technique. It proceeds, in addition to the previously observed ''hydride transfer'' pathway resulting in t he C2H5+ ion, by at least two other channels. ''Methylene transfer'' r esults in the isotopic C2H2D3+ ion, and ''eliminative condensation'' a ccompanied by molecular hydrogen ejection results in several C-3 ionic products. The reactions are investigated as a function of the collisi on energy, and their possible mechanisms are discussed.