**5. Conclusions**

In summary, the theoretical evidence demonstrates that both a 14-electron L2 M complex and a 16-electron CpM′Lcomplex with a better electron-donating ligand, L (such as NHC), result in a smaller value for ∆*E*st and allow a more facile oxidative addition to the saturated C─H bond. This theoretical study also demonstrates that, in terms of the VBSCD model, the ∆*E*st value is a useful foundation for predicting the relative magnitude of the activation barriers and the reaction enthalpies for the activation of an imidazolium cation by L2 M and CpM′L. Although the computed magnitude of the barrier and the predicted geometry for the transition state for these reactions are dependent on the level of theory that is used, these qualitative predictions are in good agreement with the theoretical results that are presented here and with the available experimental observations.

It is hoped that this study will stimulate for further research into the subject.
