| The study of appropriately designed synthetic models can lead to fundamental chemical insights for enzyme structure, spectroscopy and reactivity. As is relevant to the research described in this dissertation, we review copper proteins, their active site chemistry and synthetic copper coordination chemistry.;In Chapter 2, we describe the chemistry of new disulfido-dicopper(II) complexes, formed by the reaction of elemental sulfur (S8) with reduced copper(I)-complexes of either tridentate (side-on Cu2S 2) or tetradentate (end-on Cu2S2) ligand systems. Substrate reactivity studies reveal that the end-on Cu2S2 provides a nucleophilic S22-- moiety, in striking contrast to the electrophilic behavior of side-on Cu2S 2.;In Chapter 3, oxidative N-dealkylation reactions have been described from hydroperoxo-copper(II) species when formed within a tripodal tetradentate ligand framework possessing a pendant dialkyl amine substrate. Such a reaction mimics the monoxygenase activity occurring in the copper enzyme PHM. Observation of a product based alkoxide-Cu intermediate and determination of a reaction kinetic isotope effect provide further insights.;In Chapter 4, a trinucleating ligand which employs tetradentate chelates as their copper binding sites was explored in the hope of modeling the active sites of copper-cluster containing enzymes. Resonance Raman studies of the CuI3/O2 adduct(s) confirmed the formation of peroxo entity along with superoxo species. Reactivity of elemental sulfur and CuI3 forms a dicopper-disulfide complex.;In Chapter 5, a strongly electron-donating tripodal tetradentate ligand was successfully employed to generate an end-on bound superoxo-copper(II) complex (rR spectroscopy). The first demonstration of CuII(O 2--) oxidative reactivity with exogenous substrates, likely involving H-atom abstraction chemistry, comes with the finding that CuII(O 2--) effects the oxygenation and hydroperoxylation of substituted phenols.;Another structurally characterized mononuclear etaI-Cu II(O2--) undergoes O-O bond cleavage with the addition of hydrogen-atom donors. Net O2-derived O-atom insertion into the N-methyl group of the ligand with formation of a copper(II)-alkoxide product occurs. The superoxo-copper(II) complex is also capable of the hydroxylation of BzX (X = Br and CN) substrates leading to PhCHO and LCu IIX+ products. Further, a discrete peroxynitrite-copper(II) complex, CuII(--OON=O)+ has been generated in solution by reacting ·NO(g) with the superoxo complex. This peroxynitrite-copper(II) complex undergoes a thermal transformation to give a CuII-nitrite complex along with the formation of ca. 0.5 mole-equiv dioxygen. |
