This award by the Inorganic, Bioinorganic, and Organometallic Chemistry Program and the Experimental Program to Stimulate Competitive Research (EPSCoR) to Professor Rory Waterman of the University of Vermont and State Agricultural College addresses catalytic methodologies used to form bonds between phosphorus and other main-group elements. The research has particular relevance due to the importance of phosphorus-containing molecules in biology, fine chemicals (including chiral phosphine ligands), polymers, and materials science. Specifically, the research will investigate zirconium-mediated reactions that catalytically activate phosphorus-hydrogen bonds to form new molecules in useful and selective ways. Catalytic reactions that build phosphorus-element bonds are quite rare yet, but with a greater understanding of the fundamental processes that govern these bonds, new catalysis reactions are envisioned which will improve selectivity and afford novel products. Through a Project SEED program established by the PI at the University of Vermont, economically disadvantaged and underrepresented minority high school students will be encouraged to participate in summer research alongside University of Vermont graduate and undergraduate students. The PI will also develop a new general chemistry course directed at educating undergraduates in civic science literacy with the goal of reducing the difference in understanding practical science between science and non-science majors.
This award supported the investigation of catalysis using the metal zirconium in reactions that utilize the element phosphorus to prepare new molecules. The overarching goal of the project has been to discover and understand chemical reactions that more efficiently utilize phosphorus as this is a limited resource and an element essential for agriculture and health. Catalysis is a method to facilitate chemical reactions that is more efficient or "green" than conventional routes. Zirconium was chosen as the element to facilitate these reactions as it is relatively abundant and underutilized in industrial processes. Investigations under this award considered three different reaction types: dehydrocoupling or the forming chemical bonds by loss of hydrogen, a synthesis of phosphaalkenes or molecules featuring carbon–phosphorus double bonds, and hydrophosphination or the net addition of phosphorus and hydrogen across carbon–element multiple bonds. In all three cases, great strides were made in understanding these transformations, which is essential to continuing to discover new reaction chemistry that may yield marketable processes (i.e., economic development). More specifically, investigations of phosphine dehydrocoupling have given greater understanding and scope to this underutilized transformation. A key advance is the discovery of polymeric materials resulting from dehydrocoupling that may have interesting electronic properties. The synthesis of phosphaalkenes was expanded to a number of substrates, and it was found that the phosphorus-containing molecule could be liberated from zirconium with addition of an electrophilic reagent. Phosphaalkenes are already of interest as known precursors to polymers, but these molecules are challenging to prepare. Hydrophosphination with zirconium was expanded to include primary phosphines or those with only one organic substituent. These precursors have the potential to yield multiple products in hydrophosphination, but with simple tuning of conditions individual product can be prepared in high isolated yields suggesting that preparative routes to organophosphines may be accessible with this methodology. Under NSF funding, this research was also a vehicle for workforce development. Several postdoctoral researchers, Ph. D. students, M. S. students, and undergraduates were involved in this work and learned valuable technical skills as a result. Several high school science teachers participated in this research as well. Numerous local high school students also participated in the research supported by this award, prompting a number of those students to pursue science in college. Another particularly successful aspect of student participation in research funded by this award was the high percent of participants from underrepresented groups in science.
