Macrocyclic ligand-complexed transition metal-oxo intermediates are the active oxidizing species in a variety of important biological and catalytic oxidation reactions. Many transition metal catalysts have been designed to mimic the predominant oxidation catalysts in nature, namely the cytochrome P450 enzymes. Metal porphyrin complexes have been the center of research as catalysts in this context. This study focuses on the synthesis of porphyrin and corrole macrocyclic ligands and the corresponding ruthenium and iron complexes which are fully characterized by UV-vis and NMR spectroscopies.
The catalytic oxidation reactions towards organic sulfides by these metal complexes were also studied. Two ruthenium porphyrin complexes were examined to be suitable catalysts in sulfoxidation reactions with soluble oxygen source under mild conditions. Iodobenzene diacetate [PhI(OAc)2] was found to be an excellent oxygen source with the ruthenium porphyrin complexes toward sulfur oxidations and excellent reactivity and selectivity are observed. Over 95% conversion is reached within 12 hrs for both systems without over-oxidation.
The kinetics of two-electron oxidations of para-substituted thioanisoles by ruthenium(II) carbonyl porphyrin complexes in the presence of iodobenzene diacetate were studied. Based on the results of a series of competition studies of catalytic oxidation reactions, in the absence of organic sulfide, the oxidation of ruthenium(II) porphyrin with excess of PhI(OAc)2 can generate the well-known trans-dioxoruthenium(VI) species. However, the competition studies indicates the trans-dioxoruthenium(VI) porphyrin complex is not likely the sole oxidant in the catalytic reactions.
Advisor(s) or Committee Chair
Dr. Rui Zhang
Yuan, Zhibo, "Synthesis and Characterization of Metallocorrole and Metalloporphyrin Complexes for Catalytic Oxidations" (2012). Mahurin Honors College Capstone Experience/Thesis Projects. Paper 380.