Determining The Inherent Selectivity For Carbon Radical Hydroxylation Versus Halogenation With Fe-Iii(Oh)(X) Complexes: Relevance To The Rebound Step In Non-Heme Iron Halogenases

The first structural models of the proposed cis-Fe-III(OH)(halide) intermediate in the non-heme iron halogenases were synthesized and examined for their inherent reactivity with tertiary carbon radicals. Selective hydroxylation occurs for these cis- Fe-III(OH)(X) (X = Cl, Br) complexes in a radical rebound-like process. In contrast, a cis-Fe-III(Cl)(2) complex reacts with carbon radicals to give halogenation. These results are discussed in terms of the inherent reactivity of the analogous rebound intermediate in both enzymes and related catalysts.