This award in the Inorganic, Bioinorganic, and Organometallic Chemistry program supports research on alkane oxidation by Dr. Pradip K. Mascharak of the Chemistry Department, University of California - Santa Cruz. A series of non-porphyrin ligands with biologically relevant donor groups will be synthesized and used to prepare iron complexes that will functionalize C-H bonds. Some of these ligands have been patterned on bleomycin, iron complexes of which have been shown to have monooxygenase activity. A second subset of ligands contains strong field donor groups to stabilize hypervalent iron centers implicated in model complexes. The third subset of ligands can accommodate ligand-based radicals. All the ligands are pentadentate and will afford distorted square pyramidal Fe(II) and Fe(III) complexes that form low spin peroxo Fe(III) complexes when reacted with dioxygen or peroxides. It is this highly oxidizing species that is expected to promote rapid functionalization of alkanes and alkenes under mild conditions. Systematic alteration of ligands will be used to find optimal conditions for oxidation of various alkanes. Reaction rates, product distributions, and stability of the catalytic species will be considered. The reaction pathway will be probed using kinetic isotope effect studies, radical trapping, and stereochemical product analysis. Various spectroscopic techniques (Raman, X-ray, EPR, Mossbauer) will be used to determine the structural and electronic features of the intermediates.
The goal of this research is to design new non-heme mononuclear iron complexes that catalyze alkane oxidations and that can also be used to probe the details of the reaction pathways. Alkane oxidation is an important process because methane and other saturated hydrocarbons are abundant and have great potential as starting materials for many essential chemicals, yet are resistant to reaction. Students involved in the project will learn a wide variety of skills in synthesis and instrumental analysis and will gain experience in an interdisciplinary effort that bridges biology and industrial catalyis.
