Addition of Dioxygen to an N₄S(thiolate) Iron(II) Cysteine Dioxygenase Model Gives a Structurally Characterized Sulfinato–Iron(II) Complex

Abstract

The non-heme iron enzyme cysteine dioxygenase (CDO) catalyzes the S-oxygenation of cysteine by O₂ to give cysteine sulfinic acid. The synthesis of a new structural and functional model of the cysteine-bound CDO active site, [Fe^II(N3PyS)­(CH₃CN)]­BF₄ (<b>1</b>) is reported. This complex was prepared with a new facially chelating 4N/1S­(thiolate) pentadentate ligand. The reaction of <b>1</b> with O₂ resulted in oxygenation of the thiolate donor to afford the doubly oxygenated sulfinate product [Fe^II(N3PySO₂)­(NCS)] (<b>2</b>), which was crystallographically characterized. The thiolate donor provided by the new N3PyS ligand has a dramatic influence on the redox potential and O₂ reactivity of this Fe^II model complex