This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Professor Charles G. Riordan at the University of Delaware to develop the coordination chemistry of nickel in its monovalent oxidation state to activate dioxygen and related small molecules. The approach combines coordination chemistry with spectroscopic techniques, augmented with computational studies, to generate a detailed understanding of geometric and electronic structures of novel reactive intermediates. Long-term objectives include advancing these new species in stoichiometric and catalytic oxidations of organic molecules. Complementary studies aim to activate elemental sulfur and selenium to produce new, soluble Ni-S and Ni-Se structures Related studies of the heavier O2 congeners, S8 and Se, complement these studies affording the opportunity to gain comparative insight into small molecule/element reductive activation.
This program aims to advance the fundamental understanding of nickel-based dioxygen activation through systematic studies designed to address issues of structure, mechanism of formation and inherent reactivity characteristics. Undergraduate, graduate and postdoctoral students will develop a range of technical skills in areas including chemical synthesis, anaerobic and cryogenic methodologies, advanced spectroscopic methods and kinetics while developing intellectual breadth in the underlying principles of contemporary inorganic chemistry. Interactions with laboratories at Wisconsin-Madison and California-Davis will expose students to collaborative approaches in problem solving.
This project sought to develop a fundamental understanding of how nickel complexes react with the elemental forms of oxygen, sulfur and selenium to generate new compositions of matter. The work is motivated by the utility of metals such as nickel to capture dioxygen from the atmosphere and incorporate it into other chemicals of higher utility and value. This work demonstrated that one type of material, a nickel-superoxide, in which the dioxygen interacts with the metal in a fashion similar, but not identical to how dioxygen binds in blood, reacts with organic molecules transforming them into more oxidized products. We sought to understand how these reactions took place because understanding at this level of detail provides information on how to improve the design of next generation systems. The examination of similar reactions with sulfur and selenium, elements that are members of the oxygen family in the periodic table, have led to a better understanding of the composition and structures of new molecules that can be prepared. These results both help us to understand the oxygen chemistry better and serve as possible sources for incorporation of sulfur and selenium in chemical synthesis. Results were reported in seven peer-reviewed publications and eighteen presentations at conferences and academic institutions. The latter list includes invited presentations at international venues in Japan, Canada, and England. A major emphasis of this research project was STEM education and the training for the next generation of individuals to contribute to, and serve as leaders in, the scientific workforce. Six graduate students were supported and two undergraduates also contributed to the project. Two graduate students have completed their master’s degrees and are employed. The other four students continue work toward their doctoral degrees. Students are exposed to contemporary chemical research methodologies and equipment. Their professional development includes enhancing written and oral communication skills and collaboration with other chemists, either within or external to the University of Delaware.
