CAS: Collaborative Research: Electronic Structure/Function Relationships in Base Metal Complexes Spanning the Oxo/Oxene and Imide/Nitrene Continuum

Harvard University, Cambridge MA

Investigators

Abstract

Supported by the Chemical Structure, Dynamics, and Mechanisms B program of the Chemistry Division, Professors Theodore A. Betley of Harvard University and Kyle M. Lancaster of Cornell University synthesize molecules and materials by converting inexpensive, small molecules into higher value-added, more complex molecules such as pharmaceuticals. To accomplish these transformations, the group uses metal-based catalysts to speed up reactions and to selectively produce desired products over less desirable byproducts. The knowledge gained from their catalysis reactions may contribute to achieving a sustainable chemical industry in the United States. The research team is particularly focused on designing and developing catalysts that substitute abundant, inexpensive and non-toxic metals for the precious and, in some cases, toxic metal-based catalysts used today. Professors Betley and Lancaster are involved in educational outreach activities to engage students at the pre-university, undergraduate (internal and external to the university), and graduate levels. The researchers organize and participate in interactive demonstrations for students at the K-12 level from local grade schools and high schools. In this project ,funded by the Chemical Structure, Dynamics, and Mechanisms B program of the Chemistry Division, Professors Theodore A. Betley of Harvard University and Kyle M. Lancaster of Cornell University examine electronic structure design for C-H bond functionalization. This collaboration between a synthetic inorganic chemist and inorganic spectroscopist seeks to provide new perspectives on the correlation of radical accumulation on main-group ligands towards base-metal C−H bond functionalization catalysis. Such information is critical to advancing both fundamental understanding as well as synthetic methodologies. The research involves the synthesis and characterization of novel metal-ligand multiple bonded (MLMB) systems that mimic biological monooxygenases that deliver diverse functionalities into C-H bond substrates. The ability to selectively incorporate functionality into unactivated C-H bonds represents an advance in converting inexpensive chemical feedstocks (e.g. hydrocarbons) to value-added molecules (e.g., pharmaceutical precursors). To this end, Betley and Lancaster seek to synthesize MLMB complexes featuring N- and O-bearing functionalities to examine and harness their reaction chemistry. Betley and Lancaster propose to leverage N and O K-edge XAS as means to probe the sub-octet character of coordinated N- and O-based ligand donors and to quantify metal-ligand covalency in coordination complexes. These data will be used to rationalize periodic trends in the reactivity (nucleophilic vs. electrophilic) of MLMB complexes across the late first transition series. Undergraduates, graduate students, and postdoctoral scholars from groups that are underrepresented in science are integral to carrying out the sustainability aims. 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.