biostudies-literatureLundahl MNNIGMS NIH HHS12710-12720https://www.ebi.ac.uk/biostudies/studies/S-EPMC11325341biostudies-literatureUnknown15(32)Converting triplet dioxygen into a powerful oxidant is fundamentally important to life. The study reported herein quantitatively examines the formation of a well-characterized, reactive, O₂-derived thiolate ligated Fe^III-superoxo using low-temperature stopped-flow kinetics. Comparison of the kinetic barriers to the formation of this species <i>via</i> two routes, involving either the addition of (a) O₂ to [Fe^II(S₂ ^Me2N₃(Pr,Pr))] (1) or (b) superoxide to [Fe^III(S₂ ^Me2N₃(Pr,Pr))]⁺ (3) is shown to provide insight into the mechanism of O₂ activation. Route (b) was shown to be significantly slower, and the kinetic barrier 14.9 kJ mol^-1 higher Chemical scienceExploring the influence of H-bonding and ligand constraints on thiolate ligated non-heme iron mediated dioxygen activation.PMC11325341R01 GM123062Kaminsky WKovacs JAPiquette MCGannon PMGreiner MBLundahl MNfalseExploring the influence of H-bonding and ligand constraints on thiolate ligated non-heme iron mediated dioxygen activation.Converting triplet dioxygen into a powerful oxidant is fundamentally important to life. The study reported herein quantitatively examines the formation of a well-characterized, reactive, O₂-derived thiolate ligated Fe^III-superoxo using low-temperature stopped-flow kinetics. Comparison of the kinetic barriers to the formation of this species <i>via</i> two routes, involving either the addition of (a) O₂ to [Fe^II(S₂ ^Me2N₃(Pr,Pr))] (1) or (b) superoxide to [Fe^III(S₂ ^Me2N₃(Pr,Pr))]⁺ (3) is shown to provide insight into the mechanism of O₂ activation. Route (b) was shown to be significantly slower, and the kinetic barrier 14.9 kJ mol^-1 higher 2024-01-01T00:00:00Z2024 Aug2025-04-04T02:50:23.172Z2025-04-04T02:50:23.172ZS-EPMC113253413914877310.1039/d4sc02787f