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Hosted by Prof. Jack Norton
New Rules in C–H Activation Revealed by the Reactivity of Terminal Co Oxo Complexes
Abstract: Transition metal oxo complexes, particularly those of later transition metals, have been cited as important intermediates in processes such as C–H hydroxylation and oxygen evolution. However, these species are highly reactive and thus often difficult to isolate and study. In this talk I will present our laboratory’s efforts at isolating and studying late transition metal oxo complexes. We have found that use of pseudo-tetrahedral geometries enables the isolation of an unusual terminal Co-oxo complex.[i] The reactivity of this species towards C–H activation is markedly different than that observed for the majority of other systems and provides experimental evidence for a new mechanistic scenario arising from imbalanced thermodynamic driving forces.[ii],[iii] We show that far from being unique to this system, such “imbalanced” transition state effects are general and are also fully compatible with quantum mechanical nonadiabatic CPET reactions.[iv],[v] Finally, we will show how tuning the relevant thermodynamic contributions to CPET reactivity allows for optimization of reaction rates.
Bio: John was born in Downers Grove, a suburb about 40 minutes west of Chicago. He acquired his interest in chemistry at an early age from his grandmother, who was a chemist at Abbott Laboratories in North Chicago. Seeking to further his study of science, John matriculated at the University of Chicago. Once there, John quickly joined the laboratory of Professor Greg Hillhouse. It was in the three years that John spent in Greg's lab that he found his love for inorganic chemistry. During this time, John focused on researching phosphine complexes of Ni, specifically with respect to their reactivity with small molecules such as carbon dioxide and carbon disulfide.
After graduating John began his graduate studies in Boston at MIT in the group of Professor Jonas Peters. His time in Boston was to be short-lived however, as the Peters group moved to the California Institute of Technology in sunny Pasadena, CA quickly thereafter. John also made the move and received his Ph.D. from Caltech. John's thesis centered around a discrete Fe complex that mediates catalytic nitrogen fixation to ammonia.
After finishing his thesis, John came to Northwestern to work in the laboratory of Dave Harris. During this time, John has focused on materials, particularly metal organic frameworks. A central theme is the ability to stabilize reactive species, such as low coordinate dioxygen adducts, within metal organic frameworks thus allowing their characterization and study.
In his independent career, John and the Anderson group have been interested in linking the physical properties of transition metal centers, particularly their spin and radical character, to reactivity and bulk properties.
[i] Goetz, M. K.; Hill, E. A.; Filatov, A. S.; Anderson, J. S., Isolation of a Terminal Co(III)-Oxo Complex. J. Am. Chem. Soc. 2018, 140 (41), 13176-13180.
[ii] Goetz, M. K.; Anderson, J. S., Experimental Evidence for pKa-Driven Asynchronicity in C–H Activation by a Terminal Co(III)–Oxo Complex. J. Am. Chem. Soc. 2019, 141 (9), 4051-4062.
[iii] Goetz, M. K.; Schneider, J. E.; Filatov, A. S.; Jesse, K. A.; Anderson, J. S., Enzyme-Like Hydroxylation of Aliphatic C–H Bonds From an Isolable Co-Oxo Complex. J. Am. Chem. Soc. 2021, 143 (49), 20849-20862.
[iv] Schneider, J. E.; Goetz, M. K.; Anderson, J. S., Statistical analysis of C–H activation by oxo complexes supports diverse thermodynamic control over reactivity. Chem. Sci. 2021, 12 (11), 4173-4183.
[v] Schneider, J.; Goetz, M. K.; Anderson, J. ChemRxiv 2021. DOI: 10.26434/chemrxiv-2021-xp9mj