Building upon Brookhart, Krogh-Jespersen and Goldman's proposed mechanism with Ir I (POCOP)(olefin) as the resting state, we explored the steps required to access that species by computational means. Besides, the isolation and crystallographic authentication of the Ir IIethylene compound 2•BAr F suggests that the same type of resting state may be present for the Ir II catalysts. Considering the Ir I and Ir II dinitrogen adducts 1 and 1•BAr F that we have employed as precatalysts, the first step towards olefin isomerization would be the substitution of the N2 ligand by the olefin. First, we explored an associative mechanism, in which the coordination of a molecule of 1-hexene to the Ir I center in 1 resulted in a trigonal bipyramidal geometry (ΔG ‡ = +41.1 kcal/mol, Figure ), which then releases N2 (ΔG ‡ = +48.9 kcal/mol). The notably high energy barrier observed is likely attributed to the necessity of populating the dx2-y2 orbital within the square planar electronic configuration to accept the olefin as a new ligand. The release of N2 is very exergonic due to the recovered square planar d 8 configuration. The corresponding barriers for these steps for the Ir II complex 1•BAr F are significantly lower (coordination of 1hexene: ΔG ‡ = +18.7 kcal/mol; release of N2: ΔG ‡ = +27.7 kcal/mol; Figure ), showcasing increased reactivity upon oxidation to the open-shell configuration.