Title: Non-native N2-ase substrates, unsaturated organics, and catalytic turnover with Sm(II)
Abstract: Building on my first lecture, this second lecture Will extend the principles introduced therein to non-native nitrogenase substrates—such as cyanide (CN–) and organic sulfides—to generalize our understanding of how single iron sites catalyze a host of fascinating reductive transformations and bond-cleavage reactions, including metal-to-carbon multiple bonds as intermediates. Relatedly, I will introduce our recent progress using samarium as a catalyst. As part of our efforts to design reductive mediators compatible with small-molecule reduction catalysis while mitigating HER, we have focused on Sm(II) owing to its privileged selectivity and desirable SmI₃/SmI₂ redox couple. Despite the longstanding use of SmI₂ in organic transformations, it functions as a stoichiometric rather than catalytic agent, limiting its practicality. To achieve catalysis with SmI₂, we have devised strategies—guided by careful thermochemical studies—that enable protolytic cleavage of Sm(III)–alkoxide bonds in a manner compatible with reductive SmI₃/SmI₂ cycling. We are now exploring photochemical approaches to drive this cycling, targeting asymmetric C–C bond couplings as well as applying SmI₃/SmI₂ cycling to the challenge of electrocatalytic nitrogen fixation.
Bio: Jonas C. Peters is Bren Professor of Chemistry and Director of the Resnick Sustainability Institute at the California Institute of Technology. His research focuses on new concepts for catalysis (including electro- and photocatalysis) with applications in renewable solar fuel technologies, distributed nitrogen fixation for fertilizers and fuels, and chemical transformations fundamental to the synthesis of organic molecules. Peters earned his BSc degree at the University of Chicago (’93), spent a year as a Marshall Scholar at the University of Nottingham (’94), did his PhD at MIT (’98), and a postdoc as a Miller Fellow at UC Berkeley (’99). He has been on the faculty at Caltech since 1999, including a brief period on the faculty at MIT.
Faculty Host: Shannon Stahl