Temperature-Dependent Reactivity of a Non-heme Fe^III(OH)(SR) Complex: Relevance to Isopenicillin N Synthase

Non-heme iron complexes with cis-FeIII(OH)­(SAr/OAr) coordination were isolated and examined for their reactivity with a tertiary carbon radical. The sulfur-ligated complex shows a temperature dependence on •OH versus ArS• transfer, whereas the oxygen-ligated complex does not. These results provide the first working model for C–S bond formation in isopenicillin N synthase and indicate that kinetic control may be a key factor in the selectivity of non-heme iron “rebound” processes.