Nonetheless, the calculated barriers are excessively elevated for the Ir I system and thus, not compatible with the fact that 1 is catalytically active at 125 °C, indicating an alternative path. In the case of 1•BAr F , although the barriers are closer to the experimentally determined ones, they are still considerably higher than expected. Alternatively, a dissociative pathway seems to be energetically compatible with our experimental observations both for the Ir I and the Ir II species. In the two systems, the release of N2 (Ir I : ΔG = +22.0 kcal/mol; Ir II : ΔG = +13.0 kcal/mol) and the subsequent coordination of 1-hexene (Ir I : ΔG = +5.4 kcal/mol; Ir II : ΔG = -2.7 kcal/mol) are barrierless processes (Figure ). To shed light on whether the substitution of dinitrogen would truly play an important role during catalysis, we monitored the isomerization of 1-hexene under argon and dinitrogen atmosphere, obtaining almost identical results (see sections 5.1 and 5.2 of the Supporting Information). Once more, these results highlight the potential of our strategy, since the Ir II metalloradical exhibits enhanced capacity for ligand substitution either through associative or dissociative mechanisms, though only the latter seems to be operating in this case. This effect resembles that of accelerated carbonyl substitution in open-shell transition metal carbonyl complexes, ( ) albeit our results are based on a precious third-row transition metal, in contrast to the known radical chemistry of first-row counterparts.