The influence of the thiol, disulfide and thioether sulfur ligand coordination in copper(I) dioxygen chemistry involving adduct formation and sulfur ligand oxidative chemistry.

摘要

Targeting metalloenzyme active site chemistry, synthetic models can lead to direct fundamental chemical insights and provide reference compounds for enzyme structure, spectroscopy and reactivity. Among previously studied models, sulfur ligand containing copper complexes have not been well studied with respect to dioxygen reactivity. Synthetic models targeting copper proteins utilizing sulfur atom(s) as donor ligands are described in this dissertation.; In Chapter 1, we review copper proteins and active site chemistry, interjecting how protein structures or function give rise to notions or motivation for model chemistry inquiries. Secondly, copper coordination chemistry is summarized in the context of the approach to and challenges involved in synthetically modeling active site chemistry.; In Chapter 2, thiol and disulfide copper(I) complexes and their dioxygen reactivity have been described. A rare example of a sulfonate cupric complex was generated from complexes reacting with dioxygen under mild conditions. A carbon sulfur bond was also generated from cuprous complexes under aerobic conditions, revealing how copper-dioxygen chemistry is involved in sulfur-phenol cross-linking reactions, mimicking tyrosine-cysteine copper protein cofactor biogenesis.; In Chapter 3, a novel pinwheel shaped cuprous ion complex, with thirteen copper(I) ions, sulfide atoms, and thiolate ligands, has been generated, transformed from a thiol-copper(I) complex. The environment about the central bridging-sulfido atom provides the first example of a distorted pyramidal construction of a Cu4S core, similarity to the CuZ center of the copper enzyme nitrous oxide reductase.; In Chapter 4, the chemistry of tridentate thioether containing copper complexes is described, as model studies for methionine coordination chemistry in certain copper monooxygenases. Under mild conditions, ligand sulfoxidation is observed in the dioxygen reactions of ligand-copper(I) complexes. Reaction of a copper(II) complex with hydrogen peroxide gives both sulfoxide and sulfone products.; In Chapter 5, we describe three new trans-mu-1,2-peroxodicopper(II) species with tridentate nitrogen-based ligands, two with an imidazole and one with a thioether as a fourth donor group. Differences in optical transitions and resonance Raman spectroscopic behavior occur, compared to that for the peroxo species derived from tris(-2-pydidylmethyl)amine, most likely due to geometry changes at the cupric ion centers.