Rearrangement and decomposition of (CH3)3M+ (M = Si, Ge, Sn) ions: A DFT study

Pathways for the rearrangement and decomposition of the (CH3)3M+ (M = Si, Ge, Sn) ions are traced by the detection of stationary points on the potential energy surfaces of these ions by the B3LYP/aug-cc-pVDZ method. All three systems have stationary points similar in geometry, but very different in energy, especially on going from M = Si, Ge on the one hand to M = Sn on the other. In addition to previously found isomers of (CH3)3Si+ which have their analogs in the two other systems, “side-on” complexes with ethane and propane were revealed for all cations studied. Predicted changes in transition state and dissociation energies on going from M = Si to M = Sn allowed us to rationalize the trends for the relative decomposition product yields observed in mass-spectrometry studies of these cations.

Why do cations I and II decompose mainly by the ethylene elimination, while III decompose by the SnC homolytic cleavage.Figure optionsDownload as PowerPoint slide