Effect of Carboxamido N Coordination to Iron on the Redox Potential of Low-Spin Non-Heme Iron Centers with N,S Coordination:  Relevance to the Iron Site of Nitrile Hydratase

The redox parameters of [Fe(PyPepS)2]-, the first low-spin Fe(III) complex with both carboxamido N and thiolato S donors in the first coordination sphere, indicate significant stabilization of the +3 oxidation state of iron. Such stabilization could account for the reactivity of the iron center in nitrile hydratase.