Frontier Molecular Orbital Contributions to Chlorination versus Hydroxylation Selectivity in the Non-Heme Iron Halogenase SyrB2.

ABSTRACT: The ability of an Fe^IV═O intermediate in SyrB2 to perform chlorination versus hydroxylation was computationally evaluated for different substrates that had been studied experimentally. The π-trajectory for H atom abstraction (Fe^IV═O oriented perpendicular to the C-H bond of substrate) was found to lead to the S = 2 five-coordinate HO-Fe^III-Cl complex with the C^• of the substrate, π-oriented relative to both the Cl^- and the OH^- ligands. From this ferric intermediate, hydroxylation is thermodynamically favored, but chlorination is intrinsically more reactive due to the energy splitting between two key redox-active dπ* frontier molecular orbitals (FMOs). The splitting is determined by the differential ligand field effect of Cl<

SUBMITTER: Srnec M 

PROVIDER: S-EPMC5310988 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature