Thiolate containing N-heterocyclic amine based ligands; Investigations of intermediates in O2- and O2 reactivity and application towards new ligand design for modelling the active site of Superoxide Reductase.

Abstract

Detoxication of superoxide (O₂<super>-</super>) in anaerobic organisms is performed by the iron (Fe) containing metalloenzyme Superoxide Reductase (SOR) via reduction to hydrogenperoxide. To understand the mechanism involved and how small molecular changes aect the properties and reactivity of SOR model complexes [Fe(II)(S<super>Me2</super>N₄(6-H-DPPN))](PF₆), [Fe(II)(S<super>Me2</super>N₄(2-QuinoEN))](PF₆) and [Co(II) S<super>Me2</super>N₄(6-Me-DPEN))](PF₆) were used in an attempt to reproduce the functionality of SOR and to characterize intermediates of reactivity. Intermediates of reaction with (O₂<super>-</super>) were investigated through spectroscopic analysis as well as reactivity with a variety of substrates. Geometric alterations resulted in the reversible binding of neutral solvent ligands to [Fe(II)(S<super>Me2</super>N₄(6-H-DPPN))](PF₆). The thermodynamics of binding were studied. Based on these observations, new ligand designs incorporating steric bulk or electron donating substituents were proposed with the goal of stabilizing and isolating intermediate compounds.