Cu-I(Py2NS) (1) is formed by addition of Cu-I to a solution of the pyridyl-thiol ligand N-(2-mercaptopropyl)-N,N-bis(2-pyridylmethyl)amine (Py2NSH). Oxidation of complex 1 by air leads to the formation of Cu-II sulfinate and Cu-II sulfonate complexes, providing a model for the oxidative degeneration of copper-sulfur enzymes. Crystal structures were obtained for two Cu-II sulfinate complexes, [Cu-2(II)(Py2NSO2)(2)](BF4)(2)center dot 2(CH3)(2)CO (4a) and [Cu-2(II)(Py2NSO2)(2)(OTf)(2)] (4b), which were further characterized by UV-vis and EPR spectroscopy and cyclic voltammetry. Furthermore, two Cu-II sulfonate complexes with the proposed formulas Cu-2(II)(Py2NSO3)(2)(BF4)(2) (5a) and Cu-2(II)(Py2NSO3)(2)(OTf)(2) (5b) have been isolated and characterized. Monitoring the oxidation of 1 by UV-vis indicates that the oxidation proceeds via a dinuclear Cu-II mu-thiolate complex (3); as an intermediate an octanuclear mixed-valent (Cu4Cu4II)-Cu-I cluster with formula [(Cu4Cu4II)-Cu-I(Py2NS)(4)(mu-OH)(2)(CH3CN)(6)](ClO4)(6)center dot 2CH(3)CN (2) was isolated and characterized by X-ray single crystal structure determination.