Intrigued by the lack of reactivity of organic bromides in our reaction, we also computed G and G ‡ for the XAT step by LBR I for bromocyclohexane. By comparing the results with those obtained for the iodo analogue 1a, it seems that the difference in reactivity can be mainly attributed to kinetic factors (G ‡ R-I = +11.6 kcal•mol -1 vs G ‡ R-Br +17.9 kcal•mol -1 ), as the process shows similar driving forces for both halides (GR-I = -13.0 kcal•mol -1 vs GR-Br = -13.8 kcal•mol -1 ).