Oxidation of Metal-Bound Thiolato Sulfur Centers in Fe(III) and Co(III) Complexes with Carboxamido Nitrogens and Thiolato Sulfurs as Donors: Relevance to the Active Sites of Nitrile Hydratases

H2O2 oxidation of [MIII(PyPepS)2]- (M = Fe, Co) complexes with carboxamido nitrogens and thiolato sulfurs as donors affords the corresponding sulfinato [MIII(PyPepSO2)2]- species. The spectral properties of [FeIII(PyPepSO2)2]- resemble those of the iron site of nitrile hydratase.