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Chemistry Department Seminar

Date:
-
Location:
CP-114A/B
Speaker(s) / Presenter(s):
Etienne Garand

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Etienne Garand will be presenting a seminar titled Probing catalytic reaction intermediates using cryogenic ion vibrational spectroscopy.

Abstract: Understanding reaction pathways and mechanisms is vitally important for the rational design of catalysts.  Toward that end, we developed a method based on mass spectrometry and cryogenic ion vibrational spectroscopy to capture and characterize the reaction complexes formed during homogeneous catalytic reactions.  In addition to experimental considerations, this talk will present recent work on model metal hydroxide complexes and the first application of our approach to study catalytic water oxidation.  We show that vibrational spectroscopy of the model M2+OH- (M=Mn-Zn) systems can be used to study the trends in the extent of charge transfer between ligand and the metal center.  Such systematic studies elucidate on the behaviors observed in the IR spectra of transition metal species and provide a framework for the analysis of more complex spectra.  To probe reaction intermediates, we coupled an in-line electrochemical flow cell to our electrospray ionization source, thereby allowing us to controllably reach each step in the catalytic cycle.  Using this source, we have successfully isolated the first few reaction intermediates in water oxidation catalyzed by the single metal center [Ru(tpy)(bpy)(H2O)]2+ catalyst.  Moreover, using vibrational predissociation spectroscopy, we characterized the structure of these species as well as their microsolvated clusters.  The results show that the solvent hydrogen-bond network around the active site can play an active role in the reaction. 

Faculty Host: Dr. Dong-Sheng Yang