We describe a general strategy for extracting complex molecular assemblies from solution and freezing them as isolated ions in a 10 K trap, where they are coated with weakly bound H2 molecules or other inert cryogenic media. This solvent is then used both to rapidly quench collision complexes involving reactive partners and to allow their structure determinations using single photon (linear) predissociation spectroscopy.  The latter is carried out with two tunable IR lasers to achieve isomer-selectivity using a photochemical hole-burning scheme. We introduce the concepts with the example of water-mediated catalytic conversion of nitrosonium to protonated water clusters, a major reaction processing species in the ionosphere. We then turn to two catalytic systems presently under study, one focused on biomimetic stereoselective halogenation and the other on trapped intermediates in homogeneous hydrogenation and oxidation catalysis based on iridium metal centers.

Cryogenic ion trapping and vibrational spectroscopic characterization of intermediates in catalytic reactions

245th National Meeting (2013)

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