We describe a general experimental method for the purpose of identifying the reaction pathways that govern the catalytic transformations of small molecules like H2, N2 and CO2. Our specific long term goal is to trap key species deep in the catalytic cycle that have been calculated or inferred to play an important role but have never been isolated. Our approach involves the development of a new type of instrument that combines high resolution mass spectrometry, cryogenic ion processing, and laser photofragmentation spectroscopy. It is an on-going enterprise as capabilities are specifically tailored to the requirements demanded by the rational preparation of fragile molecular assemblies that are too fleeting to be characterized by traditional methods of chemical analysis. We will highlight instrumental advances and applications to CO2 activation with mono- and bi-metallic homogeneous catalysts. In particular, we will highlight the Ni(I) vs Ni(II) dependence CO2 activation in a cyclam-inspired ligand platform, and explore the mechanism of H-atom attachment in a diiron analogue of nitrogenase. We also report the results on an extensive study in which we introduce a general paradigm for understanding and predicting the spectral signatures of mobile “proton defects” in H-bonded networks. Finally, we report new results from our lab on the local, molecular level interactions in modified ionic liquids. This work is carried out in close collaboration with Ralf Ludwig’s lab in Rostok, Germany, who are leaders in the design and characterization of ILs tailored for specific physical and chemical properties.

Characterization of reaction intermediates in homogeneous catalysis with cryogenic ion chemistry and spectroscopy

254th National Meeting (2017)

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