Controlling Single Electron Processes at Palladium Centers

With the support of the Chemical Mechanism, Function, and Properties Program of the Division of Chemistry, Professor Liviu M. Mirica of the Department of Chemistry at the University of Illinois Urbana-Champaign aims to develop new odd-electron reaction processes for palladium metal, which normally favors even-electron processes. The proposed research will lead to better fundamental understanding of the electronic properties and reactivity profiles of the uncommon paramagnetic (odd-electron) palladium systems, which impacts how chemists build complex molecules more efficiently. The proposed studies comprise synthetic inorganic and organometallic chemistry and physical inorganic spectroscopy, thus providing interdisciplinary training and the opportunities students to develop a broad range of scientific skills. Palladium (Pd) complexes play an important role organometallic catalysis of a wide range of synthetically useful organic transformations such as C-H functionalization, C-C coupling, and C-heteroatom bond formation reactions. The vast majority of these catalytic processes formally involve Pd(0)/Pd(II) oxidation states, while the Pd(IV) oxidation state has been invoked more recently in several chemical transformations. By contrast, the chemistry of odd-electron Pd(I) and Pd(III) oxidation states is less appreciated and understood. Herein, the PI aims to develop (1) a fundamental understanding of the electronic properties and reactivity profiles of paramagnetic Pd(I) and Pd(III) systems, and (2) methods to control one- vs. two-electron processes at these Pd centers. Spectroscopic techniques including EPR, low temperature UV-vis, low temperature electrochemistry, X-ray crystallography, solution X-ray absorption spectroscopy, and computational studies will be applied to study these uncommon paramagnetic Pd systems. The specific activities include: (1) perform ligand-enabled C-H activation/functionalization studies; (2) investigate reactivity of photogenerated Pd(I) species; and (3) perform mechanistic studies of reactions at Pd(I) and Pd(III) centers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.