SusChEM: Expanding Reductive Chemistry with the Rare Earth Metals

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With this award from the Chemical Synthesis (SYN) Program of the Chemistry Division,, Professor William J. Evans of the Department of Chemistry of the University of California, Irvine, and his students will utilize the unique properties of the rare earth metals, i.e., the lanthanides, yttrium, and scandium, to explore new aspects of redox chemistry, i.e., the reduction/oxidation reactions that constitute one of the two most general classes of chemical reactions. Because the rare earth metals represent extremes in the periodic table due to their unusual physical properties, they are an excellent set of elements for expanding the limits of this fundamental reaction type. The chemistry of the (N2)3- and (NO)2- radicals, new reduced forms of diatomic molecules of biological, industrial, and atmospheric significance that were discovered via the rare earths, will be examined. The reasons why (N2)3- is so effective in forming single molecule magnets with the highest blocking temperatures known to date will be pursued. The reactivity and physical properties of seven new rare earth oxidation states, the divalent cations of Y, Ho, Er, Tb, Pr, Gd, and Lu, discovered while exploring the reductive reactions that generated the anionic radicals above, will also be examined. In addition, the recent discovery of reductive photochemistry for rare earth complexes, found in a reaction powerful enough to reduce dinitrogen to the anion (N=N)2-, will be studied.Because redox reactions are central to so many processes in life and are critical to processes important in global sustainability such as solar water splitting and dinitrogen reduction, this research can have a broad impact on science and technology. More specifically, the reductive rare earth metal based discovery of the (N2)3- and (NO)2- radical anions has implications in biological, industrial, and atmospheric dinitrogen and nitrogen oxide chemistry. The (N2)3- radical also has demonstrated a new approach to the synthesis of single molecule magnets, entities that could have far-reaching implications in energy utilization and data storage. In general, this project allows the exploration of an under-developed set of elements, the rare earth metals, which are a valuable national resource with many technological applications, while providing training to students in f element chemistry that is essential to addressing issues associated with radioactive waste disposal while training the next generation of students in this field.