CAREER: Stoichiometric and Catalytic Reaction Transformations at Group 10 Zwitterions Supported by Bis(phosphino)borate Ligands

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Dr. Jonas Peters, Department of Chemistry, California Institute of Technology is supported by the Inorganic, Bioinorganic and Organometallic Chemistry program of the Division of Chemistry, National Science Foundation, for his work under a CAREER Award to investigate whether neutral, zwitterionic complexes can mediate reactions typically catalyzed by cationic, coordinatively unsaturated complexes. Such processes are industrially important and include: the tailored synthesis of polymeric materials; catalytic bond forming reactions critical to organic synthesis and pharmaceutical drug development; and activation and functionalization chemistry, relevant to the utilization of simple hydrocarbon feedstocks. The zwitterionic strategy uses (phosphino)borate ligands to effectively tether a borate counter-anion to a cationic metal center. The potential advantages of the zwitterionic approach are: 1) Zwitterionic catalysts remove the need for a counter-anion cocatalyst and minimize counter-anion binding thereby simplifying the fundamental mechanistic studies. 2) The zwitterions should be both soluble and catalytically active in relatively non-polar solvent media; whereas, more coordinating solvents are typically required to solubilize cationic catalysts, rendering them less active. 3) Because neutral, zwitterionic complexes are expected to be less electrophilic than their cationic counterparts, they should increase reaction rates in catalytic systems that require loss of a donor ligand as a rate-determining step. Preliminary studies with zwitterionic model systems lend support to these hypotheses.Education will be integrated with research by using a case studyapproach for understanding and solving problems in frontier topics in inorganic chemistry. Interactive software, used in the research effort to perform theoretical calculations on experimental systems, will also be used in a course supplement to teach molecular orbital theory and its practical application in inorganic chemistry. An advanced laboratory synthesis course to complement the lecture course in inorganic chemistry will be developed. The research group will continue its outreach efforts to local elementary and high school students in the Pasadena and Los Angeles school districts by using laboratory tours, laboratory demonstrations, and informal discussions to communicate enthusiasm for science in a way that suggests many opportunities for younger students.Simplified analogs of industrially important catalysts will be developed. Their reaction pathways will be determined with a view toward optimizing catalytic systems. The educational program is integrated with this research and extends to undergraduate courses and area elementary and high school students.